Maybe I've lost the plot on this, but it seems pretty arrogant to self-validate totally with regards to sex, on account of it being a two-person game. There are technique things (like how roughly you grab nipples or other sensitive parts, and I'm sure you can all think of others) that perhaps shouldn't be self-validating. A certain sensitivity to your partner's preferences and the attitude that you can always make a good thing even better ... that's not seeking validation, that's seeking your partner's pleasure (and not being an insufferable a-hole).
However, if we're talking about the confidence that you are innately a desirable person and eminently f*ckable regardless of what your current partner thinks or how much they want you, that's another story.
Even so, I think "Desire is the goal only if you need validation" veers into cloud-cuckoo-land. No matter how great you feel about yourself, the honest desire of another human is the greatest aphrodisiac I can think of, offhand. It's ... what's the word ... synergistic with your own desire for them.
The problem arises when your craving for the other's desire is primarily to shore up your own ego. Or a necessity for the maintenance of your own self-image.
"Show me a completely smooth operation and I'll show you someone who's covering mistakes. Real boats rock." -- Frank Herbert