Marrying someone who is currently a prostitute is a terrible idea. He will literally cheat on you as part of his job. You also open yourself up to all kinds of diseases that he can bring home. And what about kids? What does that teach them? And when they go to school and get to know other kids and make friends, what are they going to say that their daddy does? The teacher may even call Child Protective Services on you.
Marrying any unbeliever is a bad idea for the Christian. 1 Corinthians 7:39 tells us this outright, but 1 Corinthians 7:32-34 describes why.
I want you to be free from anxieties. The unmarried man is anxious about the things of the Lord, how to please the Lord. But the married man is anxious about worldly things, how to please his wife, and his interests are divided. And the unmarried or betrothed woman is anxious about the things of the Lord, how to be holy in body and spirit. But the married woman is anxious about worldly things, how to please her husband.
If a Christian marries another Christian who wants to please the Lord, then they at least have some congruence with pleasing their spouse and pleasing the Lord, because both of them will have the Holy Spirit.
As to outreach, yes Christians can be friends with unbelievers to bring them to the Lord. Jesus was a friend to many sinners. But he didn't "flirt to convert." A line has to be drawn with those interactions.