I think it's all a personal thing. On thing I didn't think about until fairly recently... I always grew up with the idea that promiscuous people were people of little morals (which I think society in general conveys as a message a lot) but after I got more understanding of the difference between romantic attraction and sexual attraction, I realised these people may not have a desire for a relationship, or not a great desire for a relationship, but may still have a strong sexual desire and therefore that leads them to go through with sex but not a relationship. Others have a very strong desire for a relationship and recognise the idea that their sexual desires can be combined with a partner and use intimacy as an extension of emotional love (to some degree, this might also have been conveyed by society) and so their love is enhanced by doing it with someone they love. As for the person who wanted to lose their virginity while in love and then do whatever, I might speculate that she is of the first type that I mentioned but possibly has had it installed into her that virginity is special and should be lost in love.

I guess in short, you don't need to be in love to have sex, but if romance means a lot to someone, they wouldn't want or be inclined to have sex with someone they weren't in love with.