Guy was a nice guy but kind of Dorky. He falls for Mickey and things are crazy in the beginning but eventually they work out. Than when Mickey finally shows some interest and she gave him enough chances he backs off. She made attempt after attempt but rather cheat on Mickey with the blonde while they were dating and had no care about it. He pretty much deletes Mickey from his life and when gets dumped takes Mickey back out of desperation.
shareI think his sh_ttiness becomes more apparent over the course of the season. It really starts to look bad for him when he takes Mickey to the magic house and sulks when her reaction deviates from his expectations. Then he starts hooking up with a co-worker even though he still holds feelings for Mickey. Then he develops a superiority complex and makes a disastrous scene in the writers' room. But throughout all of this misbehavior, he doesn't have a single moment of introspection.
Mickey is deeply entrenched in some self-destructive habits, and definitely comes through as abrasive and insensitive at certain moments, but on balance I don't think she is more unlikeble character. Which is why the final scene of the season is pretty hard to digest considering it's essentially her expressing contrition for all of her wrongdoings and ingratiating herself to a guy who's proven himself to be a Nice Guy (tm) that should be actively avoided.
http://www.youtube.com/watch?v=opcKTe7ePgk