Here's another answer!

a) we want to be social

It's in our nature to want to be around other people. It helps us feel safe, create a sense of belonging, is amusing, and provides us with rich experiences that are hard or not possible to achieve on our own. Lots of simple reasons why people want to hang out.

b) but we have an ego

But everyone is walking about with a very intimate/personal concept of self that instructs them how to behave, how to feel, how to respond. Our feelings and thoughts in each moment are shaped by our sense of identity. Our identity isn't actually a fixed, immutable thing. It is constantly shifting, working to conform or be different or just prevent itself from collapsing entirely. The self responds to the environment the same way out bodies do.

c) being social

So we're home alone and wanting some company because we're feeling lonely, but then we arrange ourselves to spend time with others and suddenly our self is on high alert because it's being observed by others. Am I being genuine? Do people like me? Am I talking enough, or too much? Do I look ok? Did I wear the right clothes? Can I share this opinion? What should I say about that? Every conscious thought and unconscious pattern is at play, pulling and poking your sense of self and it can be disorientating and scary.