@OhNoWhatYouGonnaDo
Going against the grain here, but if I were in a committed relationship with someone who had a lot more disposable income than me, I would expect them to subsidise holidays and meals out. When I was in my final year of uni and earned nothing, my long-term boyfriend was earning £30k a year and he paid for two holidays and several meals out, and I thought that was right and proper.
This...
Also, I don't think 9 months is a 'new' relationship (particularly when both parties are that bit older).
IMO you've been given a bit of a hard time here OP which isn't deserved. Too many people are saying you 'expect' him to pay, in an entitled kind of way, but I didn't read your post in that way. I read it more that you're thinking if he wants to go on this exact holiday, which is out of your budget, and he can afford to pay for you as well it wouldn't hurt if he did.
He suggested the holiday, not you, and he chose the location/facilities so completely influenced the price bracket. And it's soooo easy to get caught up in the moment when looking at holidays! When we reflect and think of all the costs involved, loads of us come back to earth with a bump!
Hopefully you'll be able to agree a compromise that you can afford (if you actually CAN spare anything for a holiday) OR (because he wants the holiday, hence suggesting it) he'll offer to pay. Turn him down if it means you've got to pay it back as why should you be in debt to him to go on a holiday HE suggested? If you've got to get into debt at any time it should be for something YOU or your kids need/want, not to pay for his choice of holiday.
Maybe he'll end up going alone, maybe he'll end up paying for both of you, or maybe he'll go with a mate who can afford it, but you aren't being unreasonable to think someone with a far higher expendable income could pay for both of you to go on a holiday he wants and suggested.
You'd be unreasonable to expect him to pay for you to go on a girl's holiday without him and with a load of mates, but not unreasonable to think he could pay for you to go on holiday with him.
PS - with 3 teens at home please bare in mind the possibility they will have a party while your away!! That could end up costing a lot! Hopefully they're not the parting sort and/or you've got family who can keep an eye on them.
I really hope that you get this all sorted OP.