Something's Gotta Give (IMDB) (Netflix)
A romantic comedy for grown-ups, with grown-ups in the lead roles, assuming you consider Keanu Reeves as adult as Diane Keaton and Jack Nicholson. Keaton's a playwright who believes that love won't happen again and Nicholson's a confirmed bachelor for whom the milk is flowing freely. They meet cute when Jack dates Keaton's daughter, and are forced to spend time together when he becomes an unwilling house guest for a few days. When Reeves creates some stirrings in Keaton when he wants to become May to her September, and we're off and running.
This film has gotten a lot of points for showing people of a certain age doing what the rest of the movie industry considers appropriate only for the under-40 crowd, and so it should. Keaton and Nicholson are fun to watch together, and Keanu's not too much of a distraction. Writer/director Nancy Myers could have been a little more ruthless in the cutting room (surely there's a rule against films in this genre going over two hours), and some of the humor is maybe a little too "aren't we naughty?" for male tastes, but in all, a pretty successful outing.