For some people they have feelings like they'd rather be off on their own at home no matter who they're with. I know I can sometimes experience this even at family gatherings and I love my family to death and enjoy them. It's just that you're naturally uncomfortable in social settings.We all need a mix of alone time and social times, if the times you've allocated to being sociable don't seem equally attractive as the alone times I'd still say you're mixing with the wrong crowd, or trying to force yourself into socialising more than your natural need to socialise. As long as it's not hurting anyone's feelings (a wedding for instance) if you want to go home why not just go home and not agonise over it?
This is a great thread and I've been able to identify with the feelings of all those who've posted about being this way themselves. There's nothing I enjoy more than spending time by myself. Ever since I can remember I've avoided parties and going out to the extent possible. I'm incredibly shy and I feel awkward having extended conversations with people. I also don't think it's something wrong with me and I've never felt the need to be more sociable.