It's just utterly ridiculous the amount of money people are expected to spend on stag/hen events.
It's not only the money, it's the time off work and for some reason far too many couples getting married forget that it's not "just" the cost/time of the pre-wedding holiday (disguised as a hen/stag do) but the cost of the wedding as well (outfits/presents and often hotel accommodation plus money for drinks).
It's all too common to expect prospective guests to spend over £1k on attending a single wedding by the time everything is factored in.
They also forget you might have other obligations because theirs is the only wedding that matters (never mind obligations of your own with your own family).
I still slightly shudder remembering my late 20's to mid 30's where a year didn't go by without multiple weddings in my social circle.
If I'd attended all of them and the associated pre-wedding holidays I'd estimate I'd have spent more than £30k.
Frankly I could have afforded the money but I sure as hell didn't want to spend 25% (or more) of my annual leave on "holidays" to a destination I'd not personally have chosen in the company of some people I'd cross the road to avoid - at the expense of going to places with my family.
So basically I learned early on to say thanks for the invitation but I can't attend. Don't give a reason they can chip away at. Just say it's not possible and repeat.
Truth is most people dread these type of invitations but fear offending by saying no.
You need to turn it in it's head an think why the bride/groom isn't afraid of offending/embarrassing/bullying their supposed closest friends by spending their money on their behalf.
When I got married my MOH asked what my hen plans were. I said don't worry I'll sorry it - plan being a night in a hotel/spa an hour away where we can have some treatments in the day and a lovely meal in the evening and go home the next day (and I'm paying for it). Her response was "thank fuck I don't think I could stomach another week in Ibiza" and I knew exactly how she felt (she did similar when she married about 6 months later re: a local one night event).
So big girl pants on OP and stick to your guns.
It's cheeky as hell to bully people into spending significant amounts of time and money in this way.