The only lens through which you can understand someone else is your own. Which is why it's often hard for us to understand or connect... but not impossible.
Building your network, connecting, making friends, soliciting champions, getting closer, understanding those who won't move closer... it's iterative and slow and often unfolds in unexpected ways. And yet, no one with a solid circles of companions and peers around them ever seems to complain :-)
Sometimes we wonder about the 'hidden' motivations of those around us when things aren't going well ... or assign not-so-nice motivations to those not supporting our efforts or style. But really, we are simply attributing our own 'what-I'd-be-meaning-by-that-if- it-was-me' or even thinking the worst because we assume others think the worst of us.
Really, sometimes it is just the best the other person can do. The choice remains ours to keep trying, to explain, to decide to shrug it off or to actively retaliate to the perceived situation. But I always try to remember that, short of hiring a mind reader, I don't know why someone is not playing 'nice'. I can guess... but I don't know.
So maybe the anger or bitterness or just plain obtuseness has nothing to do with us personally. The only thing to do is make sure those filters are removed from our own lenses and choose how to move ahead. Our own motivations are the only ones that we can control.