I think disillusionment can occur on both sides when we take things personally and think, "What did I do? Why's that person mad at me?"
It's usually not about that one particular person when we check out, but it's usually about us, and even I'm guilty of it sometimes.. I guess that's a part of communication/miscommunication. That is why my motto is: "Live and Let Live."
I always think of the bumper sticker in Forest Gump: "Shit Happens."