Lot more to it than porn.
I think feminism has played a huge role in it (i.e. who needs a man anyway). The movement has sought to emasculate and virtually eliminate men. If men think we don’t need them, then why would they want to marry?
Some men have fallen into the trap and now want a woman who doesn’t necessarily hold to traditional roles and values. I know a couple of men like that. One never married and has two kids. The other is divorced with 4 kids. They are both players and don’t see any value to women other than for sex and hold no interest in marriage.
Stinks for women like me who value marriage, want a man who is a man (not a girly man, he doesn’t have to share his feelings), and embraces the differences between men and women.
Men are always looking for their one true love. When they are interested in a woman and find that she sees them as merely a "candidate," so far as they're concerned that woman just became a piece of meat.