I don't know whether this is actually a geographical culture thing or not, but doesn't it seem like North American business people feel the desire, for some reason, to leave every situation feeling a clear sense of "win"? Sometimes it feels like people only feel like they're getting a good deal if they can slightly screw you over a bit? Why such the animal instinct when it comes to negotiating deals?
I find it ironic because in one breath people will preach positivity and good karma, then flex their muscles with the next.
Where does culture exist that each party can walk away with their own W. More importantly, you should walk away feeling good about what the other party gained.
Unfortunately, this isn't how it works in the real world. When I come across somebody who has clearly had their trust betrayed a few times my first gut reaction is that I feel bad for them. It's like a rescued animal who seems cuddly, but underneath is a bit vicious and overprotective because it's now part of their DNA and they think that nobody is on their side.
But come on now! Get yourself up and have some faith. Not everyone is trying to rip you off and you have to approach new people sans judgement. Otherwise, you're going to miss even more opportunities because you're too busy keeping your walls up.