You know, I can totally see the points other people are making here, but I still have to disagree. Chet is Chet. He won K & M's friendship, and Arron's interest, with his unstinting compassion and integrity. Had he been less noble, he probably could've found a way to snap up Kendall into some kind of short-term relationship but he didn't. He held off, in case Kendall's straight best friend came around somehow.
For better or for worse, Moondoggie does what he thinks is right, and if that means he's not going to toss his naked, weeping, disoriented ex out the door... I'm just going to have to support him in that. If Arron is a good match for Chet, then he'll find a way to deal. I may be wrong, but I don't think Chet will be punished for his decency by some awful outcome with Arron. Let's see.