All I can say is, if people don't want to go out of their way to include you, then don't go out of your way to include them. Some may view this as childish, but honestly it's not worth the time including people who have no interest in including yourself in something. Chin up, Ellen. You're going on vacation, they're just sleeping and probably talking about people behind their backs. I mean, that's how it usually goes right?
Anyway. I hope my advice somewhat helped you. If you ever need to rant, you can go ahead and rant to me. I'm open about it.