A few years ago my parents moved in with us this was due to my mum being diagnosed with a terminal illness which she has passed away from over the summer. It was a slow decline and she passed away peacefully at home.
Now my parents didnt have a loving relationship, more like a friendship/partnership they didnt get divorced as they are of a generation where you stay together unless there are problems (affairs, violence etc) but not being in love with each other isn't a reason for divorce.
Now since my mum has passed dad has met someone quite by chance and having been without someone to love and it being a very difficult few months has fully embraced his chance. I am really happy that hes has been given this chance to enjoy his remaining years. She lives a fair distance away so has already been to visit her. While he was up there an opportunity has come up for her to visit him here and he wants her to be able to come and stay with us for the weekend sometime soon. Now I told him before he left that while I am happy for him and would be willing to meet her that I would not be happy with her staying over for a few reasons 1) I've just lost my mum who was also my best friend I'm not ready for someone else to be here as I'm not ready to fully accept she has gone yet. I can still picture her being here and still talk to her as though she might be just behind me. 2) I have social anxiety to the point where I dont have any friends other than my husband and dad now that I dont have my mum. So someone I have never meet staying all weekend is totally overwhelming me. 3) I have small children which is many reasons in itself.
I asked for time and imagined meeting her over Christmas as we have family that live near ish to her and facetime a few times then have her stay with us around March/April when we have all got to know her better and I've fully grieved for mum.
Now because dad lives here and pays some rent/contributes to the bills he thinks I'm being unreasonable and that she should be allowed to stay.