Firstly, and don't take this the wrong way, not everyone with friends is out with them on a Saturday night. Some of us are too poor at the moment. :P Secondly, no one except your family expects you to have fun at family gatherings. It's not unusual to feel bored and dissociate from what's going on. Staying cooped up all summer holiday by choice is a matter of personal preference, but if you find it's happened accidentally, try organising some cheap days/nights out. You obviously want to socialise, so it's not like you have some sort of crippling social phobia. Just put tonight down to experience, accept that families always, invariably, make you feel like ****, and make more of an effort to get out of the house, even by yourself.