ooh, oooh, I know! Help her become exquisitely competent in this area!
I realized that I had some doubts about my skills, abilities after all those years with my critical husband. I was lucky enough to have a good friend, who considers himself quite skilled-- and who was quite willing to help/coach me. I literally set some goals in this area. I am a goal setter type person, it keeps me organized and focused on what is important to me. Well, this year, I had a goal category specifically about sex-- basically to channel enthusiasm to bringing my skills to "art form" level.
If she doesn't want to be mediocre, then help her learn to be earth shattering good! You both win.
Never try to teach a pig to sing. It wastes your time, and annoys the pig.
