It only takes a little bit of clingy... girls hate that because it shows insecurity. If a guy is clingy, he's not challenge at all to a girl, and we don't want what we can have easily.. we want what we can't have very much however. If you really wanna have a girlfriend AND keep her, you need to keep her on her toes.. make her see she's lucky to have you, and that she shouldn't take it for granted. And give her space to breathe, don't smother her with affections, she'll be running for the hills!