I hear this a lot from people who feel rejected. I have felt it myself.

The thing is, people are very complex objects, and a close relationship means two very complicated objects in close proximity to one another. Sticking the spatial representation, a UK plug won't fit into a US socket. That doesn't make either the plug or the socket not good enough: they both do what they do well, but only when paired correctly.

So, don't feel that you're not good enough if someone turns down your offer. You're the right plug; you just need to find the right socket.

And notice something else: they are turning down your offer, not you. Lots of people, especially in the States, seem to think if you make a pass at some one and they decline, you cannot be friends after that. I disagree; many people can be friends after many things.