ENOUGH?

When do you say no, when do you stop trying? I like the guy, he likes me, we see each other regularly, but our goals differ. Do I stop wasting time or do I just enjoy the moment. Will he change or will I change? Will we naturally drift apart, or will the relationship change to friendship. I need friends, I want friends, but I am bad at friendship! I scare people away with my insecurities, I push away those I have feelings for, why? Because I am afraid and insecure! How do I become secure and unafraid? I need this to survive, survive my career and my personal life! How! Help!