Am I in the wrong? Wwyd?

N.

Bf and I have newborn. I don’t own the house we live in (it’s his solely). His 9 year old daughter has 2 rooms (her own room and a playroom) She only is with us every other weekend. There is a spare bedroom that was his moms but she has moved out of state (I don’t foresee her moving back in). He wants the kids to share a room once we transition our kid out of our room.

I refuse to allow that. My argument is to use the spare bedroom and move his moms furniture to the playroom downstairs, which would eliminate the playroom.

I was getting a lot of pushback/excuses from him. He finally agreed but now I’m feeling guilty.

Am I in the wrong? Wwyd?