That's something that will be brought up in a future chapter, because of course, Severus does resent her for marrying his arch rival.  She forgives him a few months before they are betrayed, it takes Voldy a few years before he actually pieces together the prophecy to the point where he's certain he should act upon it.  Before that he's too busy killing and gaining power to study the prophecy closely, but once he does . . .and I agree with you about how abruptly Lily broke it off with Severus, over a slip of the tongue and the fact that he was hanging around with some not so nice people.  That would have made me mad for a time, but once my friend apologized, I'd accept it and then try and help him see what a big mistake he was making and offer my own friendship in compensation.  But then, I'm a forgiving sort of person.

That moment is coming, in about two to three more chapters.