I'm not bashing Haley as a character, just in this particular scene. I just felt she was expecting the worse out of him .
I agree later, after she talked it over with him and said "there better not be anything more" -- then she has a reason to be upset. He definitely was a dummy when it came to telling her about how she was coming on to him. Nathan isn't known for great decision making (cue Dante), but if I saw my husband in the shower like that I would yell at the woman and kick her ass then talk to my husband. It would be different if Nathan was known for dating around or something, but he never has done that with Haley as his wife.
Haley just went insane about everything in that situation. Calling for a divorce so quickly, just wanting to give up on their relationship and such. It was very odd. I don't think Nathan had done THAT much that would warrent ending their marriage or giving up on him. Yes, frustration and counceling would be important, but she just went crazy about it and I felt bad for Nathan. There was just something about Haley in that stretch of episodes that was getting frustrating. She's usually the nicest, and most confident woman on the show (IMO) and there she was just boring, lecturing, insecure woman and it was starting to bother me. Like a little too over-dramatic.