Friend & I were talking about movies we remembered from our youth when he reminded me of this 1978 film starring Alan Alda and Ellen Burstyn. It's an adapted stage play, and it reads like a Neil Simon (but it's not). The story takes place over 26 years, checking in every five years (although they supposedly meet every year). One year he's conservative and she's liberal, the next scene she's conservative and he's liberal. One year he delivers her baby. Guilt, confusion, life changes, montages establish the atmosphere of 1951, 1956, 1961, 1964, 1968, 1972 and 1977.
I guess it was pretty "racy" for 1978 but it just seemed sweet and old fashioned now.