I watched Casablanca for the first time last night. I thought I'd hate it--too close to home or something. But I didn't. It's beautiful and true. And the end is perfect. You just know that Bogart is right--she would regret any other course, so famously soon and for the rest of her life.
I think it runs on the same theme as "Samson" by Regina Spektor (infra--or is it supra, since it went before even though technically it is below? I don't know.): There's a bigger picture here than What You Want, and what you choose matters in more than your personal little love story.
I was trying to think of more contemporary films that laud this theme, wondering if it was a lost or buried concept. Oddly, the only one that comes immediately to mind is Knocked Up.