If we're still talking about Helen Noel, as far as we know Kirk never got her into the sack. She just planted a false memory in his mind using the Neural Neutralizer.
True, Kirk wasnīt in love with her before the planted memory (which she didnīt do, BTW, but Dr. Whatīs-His-Name
). But then again, we donīt know what happened at the christmas party Helen Noel is referring to. Judging by her smile and Kirkīs somewhat embarrassed reaction, they may well have ... you know