It may be best to just take Mistress America as a happy little character comedy about a group of old acquaintances who learn some things about themselves and each other and how unexpected life can be. But I keep seeing more than that in it-- a thematic consistency that may suggest a more serious intention.
The Gift is a totally satisfying movie that shifts between psychological crime thriller and psychological horror thriller, without losing suspense and fascination, and without resorting to gore or easy jump-out-of-the-dark cliches.
Trainwreck starts out with a lengthy scene of two people having sex, the man with deep emotion and the woman with such concern over technique that her continual instructions drain the situation of any satisfaction for either one of them. It later has a scene emphasizing why people do not sleep together face-to-face. It is a love-vs.-sex movie that is not shy about facing the facts of its theme.