Just watched this again last night. Surely one of the great film comedies, and one of the great pieces of awkward or uncomfortable (serio)comic cinema (cf. Leo McCarey's unheralded masterwork Good Sam, Tom Noonan's two completed films, Ricky Gervaise & Stephen Merchant's The Office, plus probably anything Albert Brooks or more by May herself have done, though I haven't seen everything). The ending really is raw and unbalanced, as the whole ostensible point of the film (romance/love/infatuation) vanishes like the illusion it was, and, pow, it's "really" about class and status and money and identity. But the film doesn't actually sketch these things out, it trusts in the viewer's own ability to connect a few dots, as well as its own ability to provide accurate signals. Grodin lies to get what he wants, and he wants what he does in order to believe more lies. The Graduate is a fine little object on many of the same issues, but this one is ten times the film, for my money.
The Farrelly Brothers (whose films I like, by the way, though I haven't kept up with their last few) are remaking this with Ben Stiller. I don't know how to feel about that.