Sure she was a bit naive believing that doctor, but she probably felt a huge amount of guilt about the state of her husband after that screening. In that time period educated people were revered, so it's not strange she believed the words of a doctor. Aside from that She probably felt isolated in that mansion and the words of that doctor only made the situation worse. I'm feeling sorry for the both of them.
I'm feeling more sorry for the ML than the FL
He didn't deserve to be sooo misérable and bé expérimented on
I feel it's a little bit her fault for trusting that doctor and not being there for her husband