Do guys realize what they had when its gone?

Guys realize what they lost when they finally slow down and learn some humility. Every man is on a heros journey at some point in their life. They think their goals are what really matters. But at some point, sooner or later, a man will learn that the purpose of his goals is to contribute back to society.

Do guys ever miss their ex?

The short answer is sometimes no, but often yes. Men may miss their ex when regret hits them, when they see their ex looking better, hotter, and/or more successful than them, or when they see their ex with someone new.