To expect that dh accepted dd is now an adult

[insanityscratching]

and dd stopped playing the "little girl" card and they both had a relationship based on the truth rather than the image that they both prefer to portray.
A bit complicated but anyway dd is 18 and a lovely if at times infuriating daughter. She is and always has been the apple of her Daddy's eye and undoubtedly plays on that at times.
We don't have the closest of relationships (too much alike I think, she's independent and stubborn and determined too) but she appreciates the fact I treat her like an adult and she can be totally honest with me.
This weekend she has gone to stay at her boyfriend's which is absolutely fine but has told dh that she is staying with a friend. I have said already that I refuse to lie for her but dh would never question what dd told him anyway.I don't feel it's my place to shatter dh's illusions tbh.
He still treats her as though she is about five and it would knock him for six that sex was on the cards (has been for a while but that's totally normal) and that dd would even think to deceive him (although I know why she would and why she has plenty of times)
It really infuriates me when if she and I clash dh jumps in to defend her like she's a little girl, dd turns on the tears for good effect and I think to myself it's all so bloody false.
So AIBU and what should I do about it?

Of course he isn't hidden away.

But that isn't the point is it? The point is the list of things that youvwould not be able to say to your dh without repercussion.
Starting with 'so dd is staying at her boyfriends house. I think we need to talk about why she can't tell you that'

I think it's not so much sides with her he automatically assumes I'm being too harsh because he doesn't think she could do wrong. He doesn't undermine me in front of her and in the past the groundings etc still stood because when we speak later he sees I'm fully justified. He has rose coloured specs on about dd that's all.
Off out now so I'm not ignoring but will read with interest later.

So why don't you sit down with your DH and have an honest chat with him, find out what he really thinks of the boyfriend and see if he realises it's a sexual relationship. My guess is that he is totally aware that it is, but just doesn't think about it. It's easier to act as though it doesn't exist rather than to acknowledge it.

When I first starting seeing DH at 19 my mum wouldn't let me stay the night at his house (he was in student accommodation). I could come home at 3 or 4 in the morning having spent all night in bed with him (and she was well aware that this was happening) but I just couldn't stay there till breakfast. It was totally and utterly ridiculous and pointless but in her mind she was enforcing her old fashioned views. It drove me up the wall but I did it as it was easier to carry on the charade than to have serious chat with her about what was going on. I'd say something similar is happening between your DH and DD.

Though I am still surprised that you and you DH have never had any frank discussions about this.

I am off too now.

But tbh I think you need to think about why you started the thread.

You have a list of why it is like this from the boys history to your dhs naivety to your dds desire to get her own way.

But you are abso loutely determined to ignore the fact that you are just as involved as they are. You created this too. Probably more culpable than your dd as she was a child when this situation was growing.

Until you accept your role in this, your excuses for not changing it are mostly nonsense and your explanations about your dh make him sound a bit pathetic which I am sure is far from true - you can't change it.

You are not a victim here. You are not passive and put upon. You can totally change it if you want to.

You just need to decide whether you want to. I am pretty sure you don't.