Besides alcohol, other drugs can have this effect. Prozac and SSRI's in general do it, probably many others. I went through this in the early 90's. It was great in some ways - Mr. Endurance - frustrating as hell in others.
As already said, just make sure she knows you're enjoying the time together. Pick a spot, kiss it, move, repeat. You can't go wrong. Get out of your head. "Lose yourself."
Oh yea, congrats!
