Torn between her husband, Laszlo, and her former lover, Rick, Ilsa is truly stuck. There is no obvious romantic ideal for her to choose, no lesser life to abandon. Both men are good men. Both love her.
There is only possibility and choice.
Set against Nazi totalitarianism both on-screen and in the real world (the movie premiered in 1942), Ilsa, Rick, and Laszlo's equilateral love triangle is an act of outright rebellion: reminding viewers that life and the people in it are diverse and full of good possibilities.
And when your brain remembers that multiple good possibilities exist, it softens towards others and yourself.
Shame stings less. Self-acceptance grows.
Rick eventually makes the choice for Ilsa, telling her that she would regret it if she stayed, "Maybe not today, maybe not tomorrow, but soon and for the rest of your life."
The heartbreak is knowing that Ilsa will feel regret no matter who she chooses. The joy is knowing that possibilities exist.