Dude, just enjoy her body and the moment. It happened once to me but, thinking backwards, now i know i was only trying to impress her and not really enjoying the moment. I was trying so hard to fuck her as her black friends did (she a 33 years old East-European sexy slut, i was 20 and she was all the time braging about how she liked to be ruled, slapped, trown against bed

and fuked by her half-metre cock black friends)... so i thought it was too much expectation on me and i couldn't handle it

neither get it hard enough to fuck her... hahaha. But i don't care, now when i am up to have sex with some lady i just enjoy her without even trying to impress her or making a big deal out of it because, after all, i think it's kind of just like AA... many guys get all uncomfortable when the time to get laid comes and i think if you just be confident and, again, enjoy her and the moment you'll set yourself apart from other insecure guys or at least make her feel at ease and satisfy her. Hope it helps
