Good for you for standing up for yourself and not accepting crappy behavior. Either your SO will step up and change things or he is not worth your time. No one should ever accept second place from their "partner" . Best of Luck to you. 

Why has your man's adult daughter moved back in with him, and why has he allowed her to marginalise you?   I agree with futurobrilliante's advice not to put up with this.  If he wants you in his life, he needs to make room for you at his house, and not allow the mini-wife to run the show.   I made myself "almost invisible" for over a decade, when my SDs came around every other weekend, I was lonely and neglected while they and their father went out and about enjoying themselves.  I do regret this, and don't recommend it at all.  I am more assertive now, and wouldn't allow myself to be marginalised in this way.  

He has to make a choice, either he tells her, your are his GF. And the queen of the house, ///or he can live by himself with his loving DD 

He can have it both ways, you are not there to warm his bed, when he can gets away from SD.  You must have " The Talk ". With BF.  Your way or the highway 

Is this man or relationship worth it?

Its soul crushing when you are in this type of relationship, and the other woman is the daughter. The emotional affair that never ends.  Yes he may place boundaries, then the mini wife continues, he turns the other cheek, and you are left feeling hurt.  Rinse repeat...This will be your life. There are a few success stories where the DH/SO does change the dynamics, but by the time the relationship reaches that point you have become scarred. I had a therapist once  describe this as "a death by a thousand cuts". Sometimes the wounds never heal.

Think hard, read up on this forum. 

I sincerely wish you the best of luck.

If your partner is unhappy with the current situation, then he needs to be the one to fix it. Expecting you to just accept that his daughter will marginalize you is asking you to carry the burden for her rudeness, and that is not what a loving partner does.

He doesn't want to upset his daughter. And HE is unhappy that you are not spending more time at his house. So the solution, in his mind, is that YOU  sacrifice your comfort so that the daughter gets her way (your stuff out of sight), and he gets his way (your overnight presence). Somehow you being uncomfortable and upset is ok with him. That tells you pretty clearly where you are in the hierarchy..

So you've learned something about him. If he's unwilling to address the issue with his daughter, then you have to decide if the relationship is enough for you as is, or if it's time to move on.

Your username says it all. You should be fedup. I left a 10 year relationship  with 5 years married because of a spoiled 23 year old, and he went back to his ex wife. Not the same story as yours, but the daughter situation was the same. It does not get better. I believe he went back because the spoiled sh*tty daughter wanted him to, so he did.

Do not be me and waste good years on someone who even for a second puts your relationship on pause for his mini wife. These men  lack balls. Like the comment above he is OK with you to sacrifice your comfort. You know why, because you are last on his list. Remember that.  YOU can be sacrificed, and he thinks that is ok. 

Find someone who puts you first. Trust me I am happier alone than being placed second.

That he allows his daughter to displace  his partner, make his partner uncomfortable, and otherwise tolerate this kind of crap from his kid does not bode well for this relationship.

With the number of STalkers who have suffered through the toxic crap associated with moving into the former and often failed family home I would avoid moving into the family home.  If this is a durable/rest of your lives relationship it would be a good idea for your SO to sell the family home, buy a new home, and make it 'your' home as a couple.  Keeping your own place until you are comfortable with the stability of the relationship, the sanctity of any home you will have together, and his ability to keep his kids under control and in their place relative to the relationship the two of you share, would be a very good idea.

Good luck.

Are you his transition woman?  As in first relationship after his wife died?   If you are , this might never work out and any training you did for him will serve the next woman he dates.  If he's worth the trouble then draw that hard line with him as spelled out above.  If he's not worth it , keep searching.  There are other men out there.  

Fedup2018, you said "Then his daughter moved back in and promptly reinstaured her way. All my things were put away quickly and in a few days it no longer felt like visiting my partner; it became his daughter's house and I really didn't feel welcome. I mentionned it to him and he asked her kindly to leave my stuff where it is, but sho chose to ignore that and continued her way. " Sounds like he is showing you what kind of daughter he helped raise...one who not only lacks boundaries but also lacks respect. Did he confront her about this? If not They are showing you who is running the show and it sure as heck isn't your significant other. If you don't touch her stuff, she sure as heck shouldn't be touching yours.  That house doesn't sound like it's big enough for the 3 of you so if he wants to keep you in his life he should insist on a move-out date for her. 

You said " don't want to get into arguments with my partner and I certainly don't want their father-daughter relationship to get spoilt because of this disagreement with his daughter. On the other hand, I feel some sort of resentment towards him because he has not acted and protected what we had started to create." A man is supposed to be able to protect the woman that he loves. If he isn't able to do that maybe he doesn't value what the two of you had started to create. At least not as much as he values his "mini-wife"  daughter. If you are truly unhappy, I would say leave, especially if he isn't able to set healthy boundaries with his daughter.

Room and Private space to remove his lover's things away to erase her?? She respects no boundaries and he encourages it!!

no way would my husband allow any of my skids to do that in our bedroom... its hard enough having skids shun you with excuse you are a stranger despite having been married almost 6 yrs and have 2 bios together...

I have been married for close to 10 years to a man who had been widowed prior. He has an adult daughter who also displayed poor behavior and entitlement. If anyone says it will get better without changed behavior and family dynamic after time has never traveled the experienced long haul.

There is no amount of arguing, sex, looking the other way that will in reality change the situation. The family home...when we got together we owned 3 homes sold them all started over in a new one...that did not change the dynamic. The only thing that will help you is if your partner keeps all boundaries firm with his daughter regardless of her behavior or choices and displays total respect for you always. He also needs to fully accept the consequences that result from doing so.
 

Chances are more likely than not she will stop at nothing when that happens. You or he cannot fully repair this one way or another likely someone has to go. It is a painful road to travel with pain and hurt that never completely leaves you even after years together there will always be painful reminders for him and yourself.

Like you, I saw signs that I thought would improve...this dysfunctional family dynamic doesn't...dealing with it properly in some way, shape, or form it is going to be ugly, and a life long situation one way or another...fact. There are many fish in the sea who are functional with healthy family situations you do not need to settle for less.
 

Im sorry you are in this situation. It is soon enough in the relationship for you to save yourself much pain and hurt. Truly live well!

Absolutely do not become invisible to her.  If I were you I would go often and be kind to her, but do not stay the night-she won't respect you, and for that matter, neither will he.  Naturally he misses you being in his bed, but how badly?  Do not stay the night there and do tell him that you will not ever until his daughter is living on her own.  Be kind but matter of fact.  It will not work if she is living at home.  And in the meantime, your being kind to a young lady who is missing her mama may win her over.   (Btw, it's hard enough having SDs, especially, even with them not living in the home!  They are territorial and their dad is around their fingers.)  Best!

You did not do this. His DD did it. It's up to him to choose you or his DD.  His DD made it so that you two can not live in the same house.  Saying that. Time to have a take with SO saying to him you are not available until DD is out of that house 

BM passes away. It sounds like this is what she's doing. Yes, she is a "mini wife" but knowing her mother has died, I think it's almost worse. There needs to be another term for this type of mini-wife to distinguish between the more popular mini-wife role and this one. Those who are dead are almost always immortalized and larger than life, and did no wrong. They always love the  one who's no longer there, and tend to forget the not so good times. It's tough living in the shadow of who used to be there.

The most troublesome thing for me is reading that your belongings were removed WITHOUT YOUR CONSENT OR CONSIDERATION. THe fact that he allowed it and neither said nor did anything about it tells much about his character. He clearly has given her all the authority and power to do WHATEVER SHE PLEASES in an effort to reclaim her territory. He will not rock the boat with the daughter because he feels she is all he has that ties him to his former wife. That is their common thread.

Here you enter the picture and dare tread on their "hallowed ground" and try to love daddy out of his gloominess, and welcome him back to the land of the living. He seemed to really enjoy that and the fact you were the one who got him from there to here, HOWEVER, what his daughter thinks, needs and wants superceds what you think, want or need, and THAT IS NOT OK.

I have not been in our situation, but I do know I would have a tough time even thinking about snuggling up next to him in bed (&you must too, since you are no longer staying the night with him, good!) knowing he has clearly communicated exactly where he ranks you in his life without even saying one word. Of course you are feeling resentful toward him. He doesn't put you first. Actions, and lack of actions speak far louder than words. Listen.

She put your things away? You are feeling some cold pricklies from her? He has done nothing?

To me - you really should re-think this relationship. He has told you without saying it, that you will NEVER be his number 1 and only.