Why do guys only change after losing the girl they really liked?

It just hurts sometimes when you see them doing everything you wanted and changing or improving their ways but only after you’ve parted ways. Now, they’ll be an improved version for another woman. Just wish that they had done that for you or while we were still a part of each other’s lives. They also somehow find a way to justify you leaving them or vice versa and making you the villain when all you wanted was clarity and really liked him too.
Why do guys only change after losing the girl they really liked?
Post Opinion