I completely agree that cheating is never acceptable. I think it's probably the worst thing to do in a relationship. Even worse than Luke getting married when he was hung up on Lorelei. But equal with him not trying during the marriage.
But I believe that Lorelei did see it as a break up. She offered an ultimatim (admittedly not the best thing) and he said that he would not marry her. She saw that as him saying that he does not really want to get married, and it really hurt her. Both her and Chris are to blame for what happened. I dom't sgree to simply blaming Chris for taking advantage of her, as she was as much to blame.
I see what you mean, but to Lorelei it seemed as if he was choosing his daughter over her. Because, as that situation stood, there was no way that her could choose both (because of Anna). Lorelei saw the marriage as a way to make the whole problem go away, she would get to know April and marry Luke. And to her, Luke regected her solution.
It was nice to see Lorelei state what she was feeling, it's just a pity that she dropped the bomb and ran, rather than explaining situations that Luke might not understand (like what Anna told her). Lorelei went wrong way before she cheated on Luke, she started going wrong when she didn't voice her opinions (as she usually does) and let resentment build inside her.
I think that loyalty and trust is probably Luke's first want in a relationship. It makes sense that he would fall in love with her best friend. Sure, Luke didn't react well to cheating.But the situation is different. He resented Nicole for not doing the same as he was, ignoring feelings and trying the marriage. Particularly as it was her idea. With Lorelei, the relationship has a much firmer base (because they were friends first).
If they can work through this, their relationship will be stronger. All problems will be out in the open. Lorelei will learn that she has to tell Luke more than she may have told other 'significant others'. And in Luke we may see a transformation similar to that which occured in Grey's Anatomy with George. Something like this had to happen for Luke to see Lorelei as more than the Fantasy and the dream girl, now they can begin to really know each other as a couple.
