Peace be unto you,
GST528i.
In the Name of God, The Most Gracious, The Most Merciful.
Well, the examples I know of involved Muslims that were not very practicing so they would date Non-Muslims. Then they would be getting pressure from their parents to marry, so they suddenly had to try to convert their significant other, since their parents would not accept their marriage to a Non-Muslim, which would be a violation of Islamic Law (with the exception of women from the People of the Book for men).
I guess it's a case of applying some of the Islamic Laws, and not others. They violate the Islamic Law by dating Non-Muslims, and then later expect that person to convert to Islam. It's really inappropriate.
It seems that your ex did not learn the lesson.

She should simply have repented to God, and then gotten marriage to a Muslim man without dating him first, and with the permission and guidance of her parents.
So to answer your question: I do not condone your ex's behavior. From an Islamic perspective, it is incorrect. An Islamic preacher (
daiee) that I knew said that dating a woman to marry her is like robbing a bank and then donating the money to build a mosque.
Plus, just from a common sense standpoint, one should not get involved with another person thinking that the other person will change, or with the intention of changing that person. Marry a person for what they are now, not what image you think you might make them into later.
What I say is that a person should convert to Islam not for marriage purposes, but for salvation. By placing a Non-Muslim in such a position, i.e. convert or else I can't marry you, there is a high chance of muddling someone's intentions. That person might convert to Islam only to marry, instead of for attaining salvation for his soul. The Quran says "let there be no compulsion in religion", and this sort of falls under that.
In the Care of the Lord,
-Saladin.