DD21 upset with me AIBU or is she

[ML5]

DD21 has a BF (23) all fine no issues there. However they are off soon to a festival next month and she wants me to tell DH that she wants her BF to stay round for 2 nights. I know she’s an Adult however this is not something that DH will agree to as he’s very old school if that makes sense. I’ve told her she has to mention herself and not to tell me to mention as it’s not really down to me to. So now she’s upset with me cos I’m not “helping her out” and according to DD21 “you have ruined my night”.
So AIBU to not mention it or is DD21 being unreasonable. I do feel that it’s not fair for her to get upset with me as I feel as an Adult she should take responsibility herself and mention it.

If the husband is entrenched in his world views, it makes no difference who asks his permission, the answer will be the same.

Nonsense. You are 50% of the decision making in the house (or should be). Either tell your daughter "it's ok by me, you can run it past your dad in that basis". Or be honest and say "sorry, I'm not keen on the idea myself".

You're being a coward and hiding behind your DHs "rules". Be prepared for your daughter to lose her respect for you!

Haven't RTFT but - your house, your rules. Doesn't matter what 'other people' do.

I didn’t read your AIBU as ‘why should I be seen as the bad one’ but now I’m wondering if this is the issue for you. Do you want to say no, but would rather your DH said it? If that is what’s going on, it makes sense that you don’t want to help her with broaching the subject with DH. Initially I thought it sounded like you were fine with it but DH wasn’t, but now I’ve read your other messages, it sounds more like you don’t want to upset DD by being the one to say no. (Which is understandable as if the case, it is hard being the bad one.)

In any case, I wonder if it would be best to tell DD that you’ll discuss it with DH and then do so. You and DH could create some new rules so she knows what she’s allowed. If she is allowed to have BF to stay, what are the house rules? You could explain the thin walls, bathroom rules/whatever else needs addressing so she can have him over without crossing any of your boundaries? If she’s not allowed him to stay, she deserves an explanation and some understanding of when she could expect to be allowed a partner over for the night.

She’s 21 for crying out loud and on top of that it’s 2025 not the 1950’s.
My daughter asked me if her boyfriend could stay when she was 19, I said yes and told her dad the bf was staying. Why can you not say yes to her why does it have to be your husband? And why is your husband so hard to ask?

I don't necessarily think it is that weird. My husband and I have an agreement with everything in the house, that if one of us disagrees with a choice - GF staying over or even just the colour of the walls - then we don't do it.

You do realise they can sleep in the bed and NOT have sex? If that's what you're worried about with the thin walls.