That kinda happened to me last week. A coworker and good friend mentioned a party being held for another coworker who recently re-married. It was way more uncomfortable for him than for me when he realized that apparently I hadn't been included. I did ask if perhaps the invites had been sent out via e-mail, because I'd had problems with receiving messages lately anyhow and might've just missed it. However, that that was not the case. Oh well. I thought the bride and I were on ok terms, but maybe she feels differently. Anyhow, I tried to reassure my friend that it was ok, and that he shouldn't feel bad for mentioning it; I probably wouldn't have been able to attend anyhow because I already had other plans (mostly true). Other than being a bit disappointed to be left out, it didn't bother me much if it was a deliberate omission, but I did walk away glad that a 3rd party was present for the conversation, so it can't be said that I ignored an invite rather than not receiving one. And if being left out is an indicator that I'm not part of the office "cool kids", then ok, so noted. I do wonder if I should send the recent bride a congratulatory card anyhow, though...