> One person tells me my problem is that I might be an asshole and you tell me my problem might be that I'm too nice...
No, what the GP actually said was
>> I wonder if you suffer from Nice Guy Syndrome.
That's not the same thing. Because sufferers from Nice Guy Syndrome only actually think they're being "nice", but they're being so in ways or from motives that actually make them, in practice, assholes. (Sorry if that's a distortion or oversimplification of the book GP suggested; I recently skimmed through it, but didn't actually get to read the whole thing.)
> Why is it so far fetched to suggest that maybe the problem is not me?
Because usually, when one person has trouble with everyone else, and goes "What's wrong with all of them?!?", Ockham's Razor suggests the simpler hypothesis, "Maybe there's something wrong with you?", lies nearer to hand.
All in all, I'd suggest you try to get that book and read it more thoroughly than I did. (And so should I.)