What was the best superhero break-up?

Often, when superheroes break up with their significant others, it is because the characters are needed somewhere else (or some other editorial fiat), so the break-up comes out of nowhere.

Sometimes, though, the break-ups work well.

What do you think were the best superhero break-ups?

I think Kitty Pryde and Colossus had a well-done break-up. They both reacted quite normally, I think. Very natural.

How about you folks?