Charlie goes to therapy where he discovers he missed Mia, the one who got away.

Two and a Half Men Season 5 Episode 15 Quotes

Mia: Charlie, what are you doing here?
Charlie: I came to get you back.
Mia: Are you out of your mind?
Charlie: Well... I got the idea from my shrink.

Charlie: I learned why I screw around so much.
Alan: Really?
Charlie: Yup... I think I've spent my whole life trying to fill the empty space in myself by, you know...
Alan: ...filling the empty space in others?