
The dude has enough money for a basement or dungeon. It’s impractical to just have it next to somebody’s bedroom like…
Disturbed Visiter: I heard so much screaming last night
Disturbed’s Friend: Oh ho ho I guess the Marquess is really passionate about his wife (wiggles eyebrows with a grin)
Disturbed Visiter: No. No. That is definitely not the case…. At least I hope to god it’s not
For my two cents I’m betting there was some sort of risk to his life when he was a kid so had to disguise himself as a girl and go live with her family for awhile. That he is the childhood friend and he falls in love with her and promises himself he’ll come back for her once he’s out of danger and has become the Marquess. Not aware of what is happening to her in the meantime. As for what is in the room I bet it is paintings/memorabilia of her like his own little memory room. I further guess he has all the notes from her as well as the old teddy bear they used in there

If it’s a bad room I don’t think he’d be letting the maid in to clean it. Also, the maid seems only to be concerned with the FL in particular not entering which makes me think it has to do with her. Also, notice how not a single person in the entire mansion is surprised the marquess picked up a commoner woman? It makes me thing he’s talked about her before and everyone in the mansion is already aware. To be clear I’m not pointing out they are nice they could be nice even if they didn’t know, but this would be totally out of the norm for a marquess so the servants would at least be surprised and gossiping a bit, but they clearly don’t seem surprised
That room the maid told her not to go in I wouldn’t be surprised that a torture chamber