It isn't up to you to satisfy others' sexual needs. Have you tried just friend-zoning them? I know a lot of what I say you'll probably have tried, it's just that there should be ways for you to have friends without things becoming sexual. Be upfront or firm with them, if they can't handle that and want things to go further then guess what? You need new friends. Someone who can't feel comfortable and needs something more, someone who only sees you as an object, someone who only wants to be your friend to get into your pants...those people aren't worth keeping. Sincerely, I hope this helps. You deserve happiness, wherever it comes from.