I should always be welcome in DP's home, regardless of who's there - AIBU?

What do you suggest he does about that? These are two adult women who do not get along. He loves both of them and presumably wants to be able to have nice conflict free time with both. He can try and force them to spend time together, but who would benefit from that? Nobody.

Something just have triggered this specific message, so what was it?
I've asked this earlier on but OP has not been willing to share, which is quite telling. I totally agree that you don't send nasty messages out of the blue.

I would love to hear the daughters interpretation of the situation.

Everyone is saying his kids come first, yes they do, but the point here has been missed. The Op has stated that she has been affected by her partner’s reactions/non reactions to his daughter’s rude behaviour towards her. She feels she should be made to feel welcome in his home even if the daughter is there. Basically he doesn’t have his partner’s back. IMO the daughter is behaving in a very immature way. Even if she doesn’t approve of her father’s partner, being civil and polite should be the least that’s expected. My ex husband has had two partners subsequent to our divorce and my adult children have, as far as I know, always been welcoming to them. He would have let me know if they hadn’t. I think the Op might find it difficult to change her feelings on this one.

That's not within his power. He can't dictate what two grown women should do. And him not being able to control his daughter shouldn't mean he has to forfeit his relationship with her. Especially for a live out girlfriend.

But if it were a son, mother, and male partner, you would surely balk at the suggestion?

She's worked it out. I have adult children and I agree that every adults money is their own. However what is her financial situation, does he give money to her? Is he generous to his youngest DD? It's strange you think he should be financially propping up your children. You'll no doubt use the same logic as to why they/you should inherit his house.
As long as he is not seeing you at Christmas etc because of her, you might need to put up with it.

He needs to sit down with his partner and his daughter and clear the air.

I worded that poorly. It seems to be the trope of a second female partner being viewed as the villain. (Not exactly a wicked stepmother trope, but in the same vein.)

According to the embedded quotes, the OP had been accused by another poster of trying to keep her partner's daughter out of her father's home. The blame for the situation is being laid a the OP's feet, when it's surely up to the father to deal with his relationship with his daughter.

I have a key to my daughter's house but it doesn't mean I should just wander in anytime I feel like it.
Eg I wouldn't turn up and let myself in if she had a party I wasn't invited to.
I think you should just stay away if his elder daughter is there. Surely that would make it better for everyone

Ok ao what has the man done wrong?

Why not just accept the situation?

His adult daughter doesn’t like you, comes to stay occasionally and on those occasions you don’t see your partner. There’s no need for you to text or have direct contact.

Why not just simply do that and keep your relationship, rather than throwing your baby out with the bath water. It doesn’t matter what his adult daughter thinks of you, since you are not in a relationship with her.

You seem to have this weird idea that he needs to prefer you or stand up for you. She is his daughter so you won’t win. Just keep out of each others’ way.

Having a key doesn’t mean you can’t respect certain boundaries. Yabu

And exactly how much money does he give you each month?

Huh? They're both women, and OP has specifically called out her DP for being weak. I really don't understand what point you're trying to make.

How old are you both op, you’ve given the kids ages, but not yours or your boyfriends,

So do I, and find it curious the op hasn’t said what it was, just about their relationship.

I suspect the age difference and the fact the op takes money from him has something to do with this issue and it’s a lot more than it costs to have him there.

I will always have my adult children as my priority, especially over a partner that I have been with for 4 years and don't even live with. If that stops any man from loving me then good riddance. No man will ever be more important to me than my children, it doesn't matter if they are 5, 20 or 40 years old.

I think this message from the daughter is probably important.

Even if you don't like someone, if you've only met them a handful of times in the last 4 years, what would you have to be angry about on a day to day basis. It's got to be pretty rare that an abusive message comes out of nowhere, with no context, but it's also a one off (or the OP would have surely said).

No one just gets up one morning and completely randomly decides to send a nasty message to someone that hasn't been in their lives for a long time. Did it follow a meeting, an argument, What's the context, because there absolutely is going to be some.

Something just have triggered this specific message, so what was it?

Its sounds like you want to compete for his love with his child. She may be 30 but she is still his daughter. The other daughter likes you so theres obviously something that has got under the older daughters skin. I do think she needs to grow up and act like an adult, but you are also being unreasonable expecting your partner to put you first. Would you really choose your partner over your child if this were the other way around? I dont think anyone can say what they would do unless they have experienced it for themselves, but as you should know, the love for your kid trumps all.

It doesn’t have to be a straight up conflict, but l think by this point he should at least have tried to intervene and explain to DD that her behaviour is upsetting to him as well as OP, and that there is plenty of room for both of them in his life
The most common position in these circumstances is that the person stuck in the middle agree and/or disagree with both parties so they say to both what they want to hear because they are tired of the pettiness of it. Of course, one or both take it that the person stuck in the middle is taking their side, which makes them feel they are winning the battle and then have a tantrum when they don't.

I just can't comprehend any grown up who gets caught into it. It really really isn't hard to just ignore any situations deemed provocative and just get on with ones own life.

In this instance, we are talking about a you ger adults whose been close to her dad all her life Vs a partner who has never lived with him, isn't keen to do so, is not sure she still loves him and ultimately has only been in his life less than 1/10th of his life. It's obvious who the balance falls on!

I genuinely thought that my husband's kids would both have their dad's best interests at heart at all times.

Gradually it became clear that that wasn't necessarily the case. When we realised that a POA was needed for him, I was put down as primary POA with his son being the back-up.

Having his daughter down as his POA would have been disastrous, though I do think that she loved him in her own way.

I've mentioned elsewhere on MN that the turning point for me was when - after I'd been caring for DH for some years I hit health issues of my own. I phoned the daughter to let her know and to emphasise that if anything happened to me, her dad would need care.

I didn't want the kids to provide hands on care - just to advocate for DH if I wasn't there. Her immediate response was "You're not thinking of leaving him are you?"

When I got the all clear and let her know, I again emphasised that her dad would need care in the event of anything happening to me. I just wanted reassurance that DH would be taken care of.

Her response this time was "But you're all right, aren't you?" And no, it wasn't a case of her checking that I was okay - that wasn't the tone. She never did tell me that that they'd make sure that DH was looked after.

I do recall letting her know at a later date (during lockdown) that DH would inherit my pension and giving her the emergency number for the local social work department if it were ever needed. I told her that she only needed to phone that number and she then agreed to do that.

I missed the bit about the financial contributions! Wow. So despite him doing that, OP you still expect to be able to be present in his home whenever you like

You can’t avoid conflict when one party is continually inviting it - in this case DD by way of her behaviour towards OP. It’s not avoidance of conflict, it’s accepting the status quo at someone elses’ expense
Oh yes you can, you don't engage. OP is doing exactly the opposite. HEAVILY promoting someone to reprimand their adult child is definitely steering thing and putting fuel on fire. OPs posts makes it very clear that she IS provoking conflict. She is calling her partner names because he doesn't want conflict. That says it all!

I’m not sure l could feel very loving towards someone who was constantly reinforcing the fact that l’m not his priority
But it's not constantly here, it's a couple of occasions a year! I couldn't love or even tolerate a partner, especially not living with me or planning to do telling me how to manage my time the very few times they come to visit me.

It's always a woman's fault.

On another thread (not one I'd started) another poster - ostensibly a woman - asked me what I had done to 'facilitate' my husband's relationship between his daughter and granddaughter.

That was the point when I gave up.

In all honesty, I'd have been here all day if I'd written down the whole tale, but there was no point in subjecting myself to more vitriol. I was daft enough to give a short answer but then just moved on.

I think I’d want everything clarified rather than ‘unspoken’. For example “ok, I’m going to keep out of the way while she’s around, although who comes to your house really shouldn’t be up to an adult who doesn’t live there, but in that case I won’t be inviting her to my house”.

Double standards are not an option!

I have been in your situation @SecretsAndLies77 and while my DP has struggled sometimes with being manipulated by his ex and his DC, he wouldn’t entertain me being excluded from his house (I have on occasion chosen to keep out of certain situations, but entirely my decision).