To say DH was rude!

I don't see it was rude but I can understand why your DD felt it was, if she is neurodiverse herself.
Maybe to her, she was talking to you both? I know that we can do this without letting people know that we're talking to all; I do it to my DP and he'll say "are you talking to me?"
I even played a game with him without him knowing. He found out when I let out a dopamine, "yes!" He said, "did I just lose a game I didn't know I was playing?" I said yes!😆😁
Maybe she had the scenario in her head...

Mine don’t. They can come in if the door is wide open but if it’s closed or just to then they knock.

Why tf should he excuse himself from his own bedroom?

You would think so but my children wander in and out to the degree I announce when im getting dressed or undressed (tbh they have started doing this too) its like they understand the need for privacy but cant connect the dots

If my son and his dad were in my bedroom I’m already in and they were talking about something they’ve talked about a million times before, I’d stick headphones on to.

Talk about taking child centric parenting to ridiculous levels that he’s considered rude for not indulging his 17yr old talking about something she apparently talks about incessantly.

Has your dh been assessed at all?

I don't know what the YABU is ..I wouldn't blame him as she wasn't talking to him

It’s his bedroom too and he was in there before dd! DD could have taken the conversation (or monologue) into her own room. Why should he move elsewhere?

Their bedroom?

I just think it's sad that he didn't try and join in. I guess if he's heard same over and over, it does get tiring, but he could have joined and steered conversation to something you all find more interesting? Putting headphones in a little rude and a bit teenage behaviour.

Maybe I'm out of touch, but are parents not allowed to have ONE room in their houses where they can have some respite from their kids?

He was rude if he stayed in the room (assuming there was somewhere else he could reasonably go) while the apparently private convo was going on without offering to leave and being told it was OK to stay. If there was nowhere else for him to go or if he asked and you both assured him he could stay, then not at all rude.

If she makes a habit of it then no.

She's a teenager so you do need to start flagging it when she repeats herself or is endlessly cycling the same conversation - it isn't great for her, and anyone who isn't her mum (as this situation demonstrates) will just get bored by her.

What a fuss about nothing. A dad sees his wife and daughter chatting in HIS room and instead of joining in ,he walks out.
He is not being rude. He is being normal. Am sure he chats to her at other times. And why does she talk about ADHD?confusing. No explanation. Does she have it?

Its his bedroom!!!

How would this have been less rude?

Today I cried so much my false eyelashes fell off. I wish I had your problems

Why should he leave, though? They could have moved the conversation elsewhere. He was in his bedroom.

I mean he could've left the room himself if he wasn't part of the conversation. But equally it's his room and as long as she can put headphones on in her room while he is chatting to you in there, then it's fine.

You’re not doing her any favours but just nodding and smiling.

You need to be gently teaching her conversation etiquette to prepare her for life as an independent person.

Friends, partners, co workers don’t want to hear her telling the same story over and over and fixating on certain topics.

No. People are allowed to switch off from what's going on around them in their own home.

You say you don’t mind and that you love her coming in but what about your DH?

For example, does she knock before entering? Check that it’s a good time for her to come and have a chat and offload to you? Or is she just assuming it’s okay and your DH is left without much choice?

I agree your DH should speak up if he’s annoyed but maybe he felt it was kinder to put his headphones in and leave you to it.

thanks for the update OP. You need to instill in her (and maybe yourself) a rule that she can knock and pop her head round the door for a "good night" but that conversations have to be elsewhere.

If someone is blethering on next to me while i am trying to relax in my own room, i'm afraid they get short shrift.

It’s not doing her any favours to allow her to monologue at you - and I say that as someone with autism who has exactly the same tendency.

She may be ND but she does need to learn about appropriate social behaviour and when to rein in her urge to talk about her special interests. I know I spent a long time boring my mother to tears as a teenager and while I know she thought she was being nice by letting me talk, it didn’t help me in the long run.

There’s nothing wrong with her having special
interests or with wanting to talk about them - but there’s a time and a place and she does need to learn that, or she will experience much worse than someone just putting their headphones in (believe me).

I would maybe start with the basics “look, dad is busy doing X so why don’t we go downstairs for ten minutes and we can chat”. Set a limit, teach her that it’s not okay to just walk into someone’s room
and talk at them - conversation needs to be a two way thing, and needs to happen when both parties want it to.