In a novel about earlier China, the prince was required to present his poop to the court doctor so that the prince could have a diet adjusted to reflect the needs indicated by the offering. Person B isn’t Chinese, is he?
Person B is very insecure, I think, and is trying to control his world and make everything safe. He regiments his own food, and wants to regiment his SO’s food—perhaps believing it will keep them healthy and keep him from losing them.
His efforts to control his world are draconian. One wonders what A sees in B. Maybe she needs his control in some way, perhaps to keep her organized and together.
Is it abuse? It depends on the relationship between them and what agreements, spoken or not, they have about how the relationship will work. She may be happy to have his advice. Or he may be afraid of losing her, and is seeking to control her by convincing her she can’t survive without him.
She’s a grown woman, I presume. She is of sound enough mind, right? She makes her own choices and if this is the kind of guy she wants to hang with, that’s her choice. It is possible for her to leave. It could be a kind of emotional abuse, but what’s that? How can you tell when it’s happening? We all manipulate others in ways we are probably not aware of. We pressure, we whine, we shame…. are all efforts to get someone else to choose to do what you want them to do abuse? Are any of them abuse? Good question. Someone should ask it.
I don’t think it’s abuse. I just think it’s a relationship I would never be a part of.