My guest is completely incensed that I'm having my sister with her (unmarried) partner to stay over for a short holiday. My sister lives abroad and I only see her on average once every 3 years. It has been difficult to understand why, but it is perhaps a mixture between not being married, just having an unknown man in the house, a bit of racism and the fact that she would have to share the kitchen with them when we the hosts are not there (a day or 2), as we will be at work. It almost got to breaking point, as I was really upset and then it got better when we finally talked about it in depth. They will move out for a bit and come back. Now she's gone back to being standoffish (which she was before we resolved the issue by talking about it). I fear that this will continue and it will be unpleasant to share the house with them. I don't want to ask them to find another host, but if I did, AIBU?