NC for this.
Some background: I've been junior partner in a small law firm for the past few years. Eight colleagues, all male.
Last week, youngest colleague comes into work and announces he and fiancee are getting married in Spain (bride is Spanish) early May. We're all invited.
Other colleagues immediately announce with enthusiasm we're all going to attend, what a great idea, we'll have a party etc.
I'm dreading the idea: colleague who's getting married and I are the only under 30s at the office, other colleagues are more late 40s-mid 50s. We get on well, but we never socialise outside work, except for the odd post-work drinks. I've never met the fiancee.
Going would involve taking at least one, possibly two (wedding location is remote and getting there would require Ryanair flight plus 1.5h train journey), days off, which I'm not less able to afford than my more senior colleagues.
I feel pressured into going even though I'd be perfectly happy just to contribute to the present and send my regrets.
RL friends say that, if I stay home, it'll look bad, workwise, as everyone else is going. Plus, they say there might be gossip as I'm single and the only woman there, and someone might speculate my not going is out of jealousy. This latter possibility hadn't even crossed my mind until my friend voiced it 
AIBU to say thanks, but no thanks or would it be better to just such it up and go along with everyone else?