There is a reason that this episode is titled "Only Child." It was a way to demonstrate how the spotlight is always on Hannah and truthfully that's how she prefers it!
In Girls Season 3 Episode 5 Hannah seemed semi-sympathetic when she and Adam attended David's funeral, only to turn it around and be typical selfish Hannah.
Guest star Jennifer Westfeldt took an entertaining turn as David's wife...yes, his wife. She claims that he was "sometimes gay" and considering he was cruising Grindr at Hannah's birthday party, I'm gonna venture to say that he had a preference for men.