That really sucks -- are there a few people in the group that you feel closer to than the others? Do you find that one on one conversations work better for you?

Since you mentioned that this happens no matter what group you are part of, is it possible that part of this feeling is based more on your own perceptions of things? That your friends keep inviting you really suggests that they *do* like you. If they didn't, they wouldn't ask you to come with them in the first place.

It really is a confusing situation, where they like you enough to invite you but not enough to listen to you. I kind of wonder if group situations aren't just like that, where people feel like they aren't heard or liked. I know that I feel that way a lot of times even if I know intellectually that it isn't really true.