I act stupid around guys I really like?

I fall for a guy really fast and pretty hard. And it sucks. I'm usually really cool around guys and most of my friends are guys but when I get that fluttery feeling around a guy I just met, everything changes. I kill my chances of ever being with him.

I get over flirty and weird, kind of creepy, sometimes mean and I push the boundaries of normal social etiquette (I'll say things way out of line).

For this reason I've never been in love. I've loved the people I've dated but it's not the same. I always feel like I'm settling. I wind up dating my friends. My friends see who I really am and I'm able to be normal around them so it just makes sense.

I'm worried I'll never be in love. Does this happen to anyone else? What can I do to stop acting so stupid around guys I want to be with?