Depends on the size and privacy of the space

3

(A week)

2

I would say like 1-2 weekends a month so like 4 days a month. Unless like Ik and am friends with their partner then it doesn’t matter so much, maybe 1-2 nights a week

2

How old is the relationship? Was it a relationship before you moved in and this was a known pattern? Is this an apartment or house? Shared living space? Does it impede in you having your own company over? There’s a million questions that could explain a million scenarios. The thing is, you’ll have to just adapt or change the circumstances. Either go with the flow or possibly just go. Or find a reasonable way to suggest they move in together so you can find a roommate that more meets your needs

1