How do you know if a guy is in love or just wants sex?

Does having sex too early in the dating phase cause the guy to lose interest (me being a female)? I assume most people will say yes…

However, what if you sense that the guy has actual feelings, but you ended up having sex too soon?

I’m very worried as I just ended up sleeping with a guy that I think I’m falling for, and I think he’s falling for me too, but I’m afraid he will lose interest now or think I’m easy. I don’t know how it happened, it was neither his nor my idea, but it just happened.

Does having sex too early destroy any chances of a real relationship?

How do you know if a guy is in love or if he wants just sex?