I've felt it a few times in the past, never with anyone I particularly cared that much about. With my girlfriend it's not like that, I respect her too much.
On the other hand, I can remember having someone give me a lustful look, and as I said in a different thread, still a virgin, I had no idea and instead of even noticing that a cute girl that wanted me was in my room with me...alone...sigh...I told her I just came back to grab another drink and proceeded to...sigh...tell her to come with me and rejoin the others...
I'd like to think God's plan for me was to save it for my current g/f. Which I did, and it worked out great. Just a long, long road getting there.