Excuse help I feel a bit bad even writing this lol ? but oh cousin is having a party next week at a local soft play for…

Excuse help

I feel a bit bad even writing this lol ? but oh cousin is having a party next week at a local soft play for their ds birthday. Me and dh are booked to go away overnight to a fabulous spa hotel for my birthday not long after. We never ever get away together, the last time was two nights two years ago after we were married lol mil is watching the kids, I cannot wait ?? The thing is every single time we're at a kid's party, especially at this place, either we or the kids get sick. Oh cousin had an easter party for the kids and I was sick for a full fortnight after it ? I know this sounds so selfish but I just don't want to risk us not getting away. We really need a break. Is there a good excuse for not going to the party? Preferably something in advance so oh cousin won't be out of pocket at all ? xx