Shared Interests

Why is it, do you think, that people in general don't seem to be able to fully enjoy things unless they have other people to enjoy them with? I know this is the case for me, and it seems to be so for most other people as well. We want to share our interests with those around us. We want our friends and family to understand why we love the things we love and, preferably, for them to love those things as well. But why? Why is it so important to us that other people share in our interests? I mean, I don't know about the rest of you, but most of the things I enjoy don't necessarily require any other people. It's not like I'm particularly interested in any kind of group activities. So why the fuck do I care if anyone else wants to watch my favorites movies or TV shows, or laughs at the strange things that I think are funny, or wants to wander around in the woods and climb on dead trees (yeah, that counts as one of my interests)?