Studying for a really hard exam is the type of "who cares" bad day thing that it's socially appropriate to tell someone you don't really know about, but it is still painful enough to cause me to go to sleep feeling tense and have really vivid bad dreams. However, literally as soon as the exam is over, whether it went well or not, I forget about how painful it was to study for it. That makes it totally different than practically any other bad experience, you know? A new and better job doesn't take away the pain of having felt stupid and demoralized in your old one. A new and better relationship doesn't take away the pain of having been dumped in your old one. Those painful things become more distant, but you don't forget them like you forget studying for an exam.
So imagine if other bad things were like studying for an exam. Imagine if there was a guarantee that you only had to feel bad about your breakup for like three days or something, and then you'd have a new and better relationship right away. I bet you'd forget about the bad experience too, faster than fast.
Kind of makes me realize something, which is this: it's not the experience itself that was so bad. It's the endless business of thinking about it afterwards.