House Calls (1978)

Walter Matthau and Glenda Jackson made two films together of which this is the first (and probably the better).  He plays a recently widowed doctor and she a recent divorcee.  He's eager to play the field after years of fidelity, but after one night's mutually agreed sex, she challenges him to stop playing around or to give her up.  Her character is an opinionated motormouth, but he loves being with her; hospital politics nearly kill their relationship as he tries to help the senile director fight a lawsuit (and a brilliant turn by Art Carney here).  Their dating is completely charming as two older people prove that not only youngsters know how to romance.  There is one particularly hilarious bit when they attempt to prove whether or not it is possible to make love with one leg on the floor as the former Hollywood censor dictated.  Matthau was always good value in a film and nowadays one can forget what a gifted light comedienne Jackson was.  I think she brought a lot more happiness to a lot more people in movies like this than she ever has as an MP!