Try to keep this short as possible!
Group of friends, six of us, one couple (A&B), four singles (C, D, E & F), three of each sex. Known each other for years, socialise as a group one evening most weekends.
A couple of times last year A&B plus C & D went out but didn't invite E & F but plastered photos of their nights out, meaning E & F realised they hadn't been invited and felt a bit hurt. No one minds people doing things in pairs, or all the women, or all the men, but if you do things with the majority of the gang but don't invite one or two, keep it off social media.
Anyway, C now has a partner, G. C&G have chats about going away for a long weekend on the coast with A&B, a place we've all been as a group but where A's dad also lives. All think great idea and agree to sort out in a few weeks. This weekend C texts B to say "shall we fix a date" and B replies "oh, we're there now, actually, A needed to come and see dad". C&G think no more of it. Until that night, of course, up on Facebook are A&B with E - clearly not family stuff at all.
C&G feel very hurt, not so much they they weren't invited although it had been discussed, but not telling them it was happening, lying to them about it and being stupid enough to be caught out lying via Facebook.
I'm F in this situation, knew nothing about it until it happened but have had C&G bending my ear about it all last night.
AIBU to think friends are often more thoughtless in these days of social media and that I should find some friends who cause less drama (I think A is a potential Wendy, too).