In 2017, my husband and I bought a house. Initially, Susan (now 16) was assigned to "room A." However, after a week of living there, she started complaining that she could hear every sound from our neighbor, who was partying a lot at the time. She also didn't like that her window faced a forest, and besides the neighbor's house, all she could see was darkness and trees in night. We ended up moving her to "room B." Room A has been empty ever since, turning into a bit of a storage room.
At the end of last year I decided to take care of it and, using only my savings, I did a huge renovation - replacing the windows, soundproofing the walls, etc., etc. I also bought new furniture, painted the walls, laid a carpet, replaced the lamp, etc., etc. Now it looks like a very cozy library/office/living room. And I love it.
But Susan isn't happy, and as soon as I started renovating, she started demanding that I give her the room back. Suddenly, she started claiming that her own room was too small (it's bigger than mine and my husband's, and the same size as our other two children), that she hated that all she could see through her bedroom window was a brick wall, and that it wasn't fair that I'd taken a room "for myself" that had its own walk-in closet and so on.
My husband is on her side, but I think it's unfair. My husband has two rooms in the basement to himself, one he converted into a gym and the other into work office. Children (7F, 12M, and Susan) have larger rooms than us, and much of the garden and main living room are converted for their needs. Furthermore, neither my husband nor Susan's mother paid a penny for the entire renovation. I did everything myself.
So I told my husband that if he cared so much, he should give Susan one of his rooms, but neither he nor Susan liked the idea, and now they're both mad at me.