Yesterday evening I got a call from a colleague who works elsewhere but for the same company as I do. Was it supposed to hurt me?

I wasn't around, so I missed it. Later I texted her, and she told me that she and some mutual colleagues were out for dinner after a team meeting. I had had guests, and hence I couldn't have joined them anyway. But my best friend was there.
And my best friend hadn't called to invite me. This colleague had. Is it supposed to hurt me? Because it did. Is my best friend ashamed of me?
He also told me a couple days back that he needs to be different around people. I don't understand why? I asked him and he said it's just how social norms are. Everyone is to be treated equally when they're around. I could ask him why is that important because I certainly don't get that equal treatment from them so why should we care about them? But it starts at argument and I get blamed for ruining our friendship so I didn't ask that.