I think it's pretty unfair of anyone to get dumped because of this, regardless of preferences. You cannot expect every partner you experience to be akin to some "sex god".
The fact is, not everyone is at the same level. If a girl dumped me for my 'lack of' sexual ability I'd be pretty disgusted with her, and needless to say she would be out on her backside (simple!).
I've had sex numerous times, and had two girlfriends in my time, therefore, I'd say I was suitably sexually experienced (to an adequate level) for most women. If that isn't enough then I would probably reconsider the sort of girl I was dating and think well...she's a bit of a ****, if she can't accept a reasonable standard of activity in the bedroom, then she ain't for me. Why should one have to change to suit such promiscuous rubbish?
I think it's degrading to expect people to be sexually superior in bed, we cannot expect each other to be man whores or sluts. Not everyone has lack of self respect of their bodies.
Deary me, where is respect and class in today's world!!