What am i doing? I feel like I'm doing everything wrong - I can't make anyone happy.

I keep messing things up, wrecking friendships. I feel like I've had to cross so many names off my friend list this year - it's ridiculous: Richard, Gav, Roon, Dave, Sarah, Jen, Kev - but then again, how good friends were they?
I've started to question everything I do - the way I act, the way I am with people. I obviously need to get a hold of this flirting thing, but then how should I behave? I just don't know anymore.