Something's Gotta Give/YMMV

Double Standard: The Movie. He dates women much younger than him? He's a dirty old man who needs to grow up. She dates a man much younger than her? She's a vibrant, vital woman reveling in her sexuality. He makes her feel embarrassed? He's a cad and a jerk. She publicly humiliates him and enshrines that humiliation forever in a popular Broadway play? Good for her, he had it coming and it was just the wake-up call he needed.
Romantic Comedy: While this film is definitely one, it could probably be enshrined as the demonstrative archetype of the genre, despite featuring characters much older than the usual. It features a wealthy, attractive man who spends half the movie being wrong about everything and getting lectured for it, and the other half desperately trying to please women and change himself into the perfect mate for the woman he wants to be with. Packed into that one sentence is pretty much every stereotype of the romantic comedy genre, and that's pretty much all the movie is.
WTH Casting: It's kind of amusing to watch Jack Nicholson bumble around being a romantic lead.