It was called GIRLS, so the guy cast members were never going to be a part of the finale. It was meant to bring us back to the presumed alpha, which was Hannah..and let it all go with her in the end.
This was the nexus of a fantasy young-adult life running headlong into a real adult-life (the viewing demo) and it turning up cold. We were all with Hannah being garbage until she needed to not be garbage...and she turned up short.
You're giving this WAY too much gravitas. It is a tv show.
You're The Worst is literally the Worst. There is nothing about that show that is even worth conversation.
Do y'all listen to Watch What Crappens Live (podcast)? They are hilarious, and the recap for this week is everything. (not sure I should link, but you can find it easily)
Mostly because we never saw a Shay/Shaena relationship, just her view of it as a cast member? They were together for almost 10 years, so there's a TON that we'll never be privvy to..
http://www.bravotv.com/the-daily-dish/tom-schwartz-triplet-brothers
More about them. I honestly have no idea if they are on "the spectrum" but they are 31 and Tom talks about them like they are 10.