yes, I wish there HAD been more of Gabe later in the movie. It WAS a lot for him to process....not only did his own brother ''help him out of the closet'' but his best friend and his brother had formed a relationship that was more intimate then his own relationship with either....he HAD to be feeling a bit left out...third wheelish...
Gabe was a compelling character, but he was necessarily shallow, all show, all bluster.
Granted he was hung over when he got to the diner, and had no idea how to deal with it, he got his point out there that it was okay and should have left it at that. The writers knew better, it was an opportunity to get in that "thing" I tried to start a thread on once and I still don't think I got myself understood.
Gabe says "Guys give better head don't they?" and starts off on this thing I have experenced many times when a straight male acquaintence suddenly gets real interested in what I do in bed. It can be off putting, and because of Gabe's shallowness he cannot see that Zach is not about all that, he is dealing with something much more profound.
Now let me ask this: Did they ever say they loved each other?