The Sex Is No Good - Should I Stay?
You meet someone, have a brilliant time, fancy the pants off them and can't wait to get to bed... Where you are bitterly disappointed. What should you do? Stay and hope for the best? Or move on before you get too attached?
Some scenarios are fixable. Technique can be taught if you're willing to school a new lover in what you like, where and when.
Ignorance about sex in general and a lack of understanding of how your sexual systems work is solved by buying them some good sex books as a present.
Harder but also possible to change are things like reshaping someone's attitude to sex. If they've been brought up to believe sex is 'bad' or 'dirty', they may need counseling to reshape deeply ingrained beliefs - but it can still be done.
Even dramatically different sex drives can be balanced if you're willing to compromise. It's not such good news if you don't think your partner's a good lover because there's no spark or fireworks (if it's not there in the beginning, it's unusual for chemistry to kick in later on).
But the only thing that's truly impossible is transforming a selfish, brutish lover into a good or even acceptable one. These people will fight you, kicking and screaming every step of the way.
So if you (poor you!) end up with someone like this, I strongly suggest you extradite yourself from the situation ASAP. If your partner is well intentioned, just not terribly good at sex, stay.