Why is it so difficult to accept that Paul abandoned his wife when he converted to Christianity? Paul is adamantly presumed to be an exemplar of singleness as an ideal, and if Paul was ever married, he must be a widower who championed singleness after his conversion on the road to Damascus. The more likely conclusion that Paul was married and left his wife after his conversion is never considered at best or vehemently opposed.

Pharisees were married therefore Paul was married

Paul was a Pharisee of Pharisees and an unmarried Pharisee is as unthinkable as a married Catholic priest.  Paul boasted of his elite Pharisee resume, and at the time of his conversion, Paul acted under authority from Jerusalem rulers, so he was not loosely affiliated with Pharisees but instead a pinnacle example of Pharisaism. And being married is an essential feature of Pharisaism (I'll leave the proof as an exercise to the reader since this is not a controversial point at this time, or a follow-up post later). 

Philippians 3:4a-6 (NRSV) "If anyone else has reason to be confident in the flesh, I have more: circumcised on the eighth day, a member of the people of Israel, of the tribe of Benjamin, a Hebrew born of Hebrews; as to the law, a Pharisee; as to zeal, a persecutor of the church; as to righteousness under the law, blameless."

Galatians 1:13-15 (NRSV) "You have heard, no doubt, of my earlier life in Judaism. I was violently persecuting the church of God and was trying to destroy it. I advanced in Judaism beyond many among my people of the same age, for I was far more zealous for the traditions of my ancestors. "

Acts 9:1-2 (NRSV) "Meanwhile Saul, still breathing threats and murder against the disciples of the Lord, went to the high priest and asked him for letters to the synagogues at Damascus, so that if he found any who belonged to the Way, men or women, he might bring them bound to Jerusalem."

Paul was not a widow at the time of conversion

The argument that Paul was always single does not logically follow because of the fact that Paul was a committed Pharisee. At that time and place, marriages were arranged (there are examples throughout the bible, including Mary and Joseph), so if Paul's wife died while he was a Pharisee, another wife would have been promptly arranged. Pharisees were upholders of tradition, and "love marriages" were not a practiced tradition. There were no social safety nets outside of the family and local tribal culture, so remarriage was necessary, especially for Pharisee leaders. It is illogical that Paul would remain a widow while being an official oppressor of all who opposed the way of the Pharisees e.g. Christians. 

Paul was not single (e.g. unmarried) at the time of conversion

Some object that Paul was "unmarried" based on 1 Corinthians 7:8 (NRSV) "To the unmarried (ἀγάμοις) and the widows (χήραις) I say that it is good for them to (μείνωσιν ὡς κἀγώ) remain unmarried as I am." However, Paul identifies with the greek word for "unmarried" and not for the word for "widows" in this verse. Additionally,  the same word for "unmarried" is used to describe a person who has separated from their spouse in 1 Cor 7:11a (NRSV) "but if she does separate, let her remain unmarried (μενέτω ἄγαμος) or else be reconciled to her husband". So in Paul's own words, when he describes himself as "unmarried" (1 Cor 7:8) it is the same meaning as someone who has left their marriage (1 Cor 7:11a) for the sake of their Christian faith. So the argument that Paul was never married is refuted by Paul's own words when he labels a person who abandoned their marriage "unmarried" as he is now.

Paul abandoned his wife after his conversion to pursue his apostolic calling

After Paul's extraordinary conversion on the road to Damascus, he says that he immediately proceeded to Damascus and remained there for 3 years (Galatians 1:18), and then spent another 14 years in Arabia before returning to Jerusalem (Galatians 2:1). Evidently, Paul did not return to Jerusalem to fetch his wife, but instead abandoned her there. We know that Paul had an influential family in Jerusalem because they are aware of conspiracy plots against Paul's life and come to his aid while he was imprisoned e.g. Paul's sister and nephew are mentioned in Acts 23:16 as coming to his aid. Although it does not say so in the black text of scripture, it is sound inductive reasoning to conclude that Paul's wife remained in Jerusalem while Paul was an outcast in the northern countries. This former hunter of outcasts, Paul, had become an outcast himself. The reasonable explanation is that Paul's wife was ashamed of her outcast husband and did not believe his conversion testimony, and therefore chose to remain in Jerusalem. So Paul's abandonment of his wife was likely mutual, especially after considering what Paul writes in 1 Corinthians 7 on unbelieving vs believing spouses.

Paul's wife did not wish to follow Paul in his ministry (1 Corinthians 7)

Evidence that Paul's wife chose not to pursue Paul after abandoning her is latent in 1 Corinthians 7:8-16, which is ironically the classic locus used to justify divorce in the case of abandonment! Is not Paul defending his own actions when he writes this passage (quoted below)? Is it not Paul, who has a wife that did not believe his conversion story, and chose to remain an unbeliever in Jerusalem without him? Isn't it telling that Paul here resorts to his enigmatic phrase "To the rest I say--I and not the lord"  that has been so cumbersome to dictation theories of the inspiration of scripture?

1 Corinthians 7:8-16 (NRSV) 8 To the unmarried and the widows I say that it is good for them to remain unmarried as I am. 9 But if they are not practicing self-control, they should marry. For it is better to marry than to be aflame with passion. 10 To the married I give this command—not I but the Lord—that the wife should not separate from her husband 11 (but if she does separate, let her remain unmarried or else be reconciled to her husband) and that the husband should not divorce his wife. 12 To the rest I say—I and not the Lord—that if any brother has a wife who is an unbeliever and she consents to live with him, he should not divorce her. 13 And if any woman has a husband who is an unbeliever and he consents to live with her, she should not divorce the husband. 14 For the unbelieving husband is made holy through his wife, and the unbelieving wife is made holy through the brother. Otherwise, your children would be unclean, but as it is, they are holy. 15 But if the unbelieving partner separates, let it be so; in such a case the brother or sister is not bound. It is to peace that God has called us. 16 Wife, for all you know, you might save your husband. Husband, for all you know, you might save your wife.

Thus Paul and his wife mutually abandoned their marriage over irreconcilable differences and this conclusion is confirmed by tradition from the early Church fathers (see below). 

Peter's "believing" wife vs Paul's "unbelieving" wife (1 Corinthians 7)

The best explanation of this passage is that when Paul chose to confront promiscuous and sensuous marital relations in the Corinthian Church, he was concerned that he would be accused of hypocrisy due to his own separation from his wife. Additionally, Paul is aware that Peter's wife did believe him and chose to follow him in his apostolic ministry, and so he was concerned that Peter's example would be used against him as well e.g. Paul, why didn't you bring your wife with you like Peter? Therefore the "believing wife" is identified as Peter's wife and the "unbelieving wife" is Paul's own wife. This is not speculation because it appears in the very text of 1 Cor 9:3-5 (NRSV): "This is my defense to those who sit in judgment on me. Don’t we have the right to food and drink? Don’t we have the right to take a believing wife along with us, as do the other apostles and the Lord’s brothers and Cephas (Peter)?" 

Church history testifies that Paul's wife was alive and active during his apostolic ministry

There are several early Church fathers who testify that Paul had a wife (or consort) that he had left including Clement of Alexandria (c. 150 – c. 215 AD), Eusebius of Caesarea / Pamphilus (c. 260/265 – 339), Ignatius of Antioch (died c. 108/140), Origen of Alexandria (c. 185 – c. 253), and others.

EUSEBIUS: "And Paul does not hesitate, in one of his epistles, to greet his wife, whom he did not take about with him, that he might not be inconvenienced in his ministry." - Eusebius, Church History, Book III, Chapter XXX 

CLEMENT: "53. Even Paul did not hesitate in one letter to address his consort. The only reason why he did not take her about with him was that it would have been an inconvenience for his ministry. Accordingly he says in a letter: "Have we not a right to take about with us a wife that is a sister like the other apostles?" But the latter, in accordance with their particular ministry, devoted themselves to preaching without any distraction, and took their wives with them not as women with whom they had marriage relations, but as sisters, that they might be their fellow-ministers in dealing with housewives. I t was through them that the Lord's teaching penetrated also the women's quarters without any scandal being aroused." - Clement of Alexandria (c. 150 – c. 215 AD), "On Marriage" Miscellanies, Book III, Chapter VI

IGNATIUS: "For I pray that, being found worthy of God, I may be found at their feet in the kingdom, as at the feet of Abraham, and Isaac, and Jacob; as of Joseph, and Isaiah, and the rest of the prophets; as of Peter, and Paul, and the rest of the apostles, that were married men. For they entered into these marriages not for the sake of appetite, but out of regard for the propagation of mankind." - Ignatius of Antioch, Epistle to the Philipians: Shorter Version, Chapter IV 

ORIGEN: "(3.) Paul, then, if certain traditions are true, was called while in possession of a wife, concerning whome he speaks when writing to the Philippians, 'I ask you also, my loyal mate, help these women.' Since he had become free by mutual consent with her, he calls himself a slave of Christ. But if, as other think, he had no wife, nonetheless he who was free when he was called is yet a slave of Christ." - Origen of Alexandria, Commentary on the Epistles to the Romans,  Book I, Chapter I, #3.

Scriptural precedent for ending marriages for the sake of faith and ministry

There is a long tradition in the scriptures of prophets and people who have left their spouses for the sake of faith. Even on the lips of Jesus: Matthew 19:29 (NRSV) "And everyone who has left . . . wife . . . for my name’s sake will receive a hundredfold and will inherit eternal life." In Ezra 10, the people make a "pledge to put away their wives" (Ezra 10:11,18). And as well in Church history, for example, St. Augustine of Hippo abandoned his wife for the sake of ministry (although he is far less defensible), and so on. And there are examples of many missionaries that have abandoned their families for years.  Charles Hodges abandoned his family for two years for a trip to Europe for ministry purposes and to visit famous theologians such as Friedrich Schleiermacher. I'm not defending all these examples, or considering them equal, but only demonstrating that this is a common occurrence in church and biblical history.

Why is it so difficult to accept that Paul abandoned his wife when he converted to Christianity?

In conclusion, there are multiple reasons why the logical conclusion that the apostle Paul abandoned his wife is never considered. Here's a few possible reasons why:

1. It is a point of embarrassment for Paul. It's okay for the other apostles to have failures, but not Paul.

2. Paul may not be used to promote singleness as an ideal

3. People with broken marriages may no longer be ostracized using Paul's example. It disables the clobber prooftexts

4. It prevents theologians and pastors with moral failings from being harshly rejected and ostracized by hyper-moralistic and voyeuristic Christian’s who cannot tolerate any personal failures.