Well it's not only that though, the servants played a good part on it too and she was already insecure in the first place and Orpheus told her that he only married her because of what his father said, granted they both fell inlove with each other after.
But after being told by the servants that she stole Diana's rightful place as the mistress of the house, Orpheus' attitude didn't help. Also the butler knew what was going on and he didn't do or say anything about it.
Everybody got complacent and it just snowballed from there.
Out of everything, I wish they would just talk about everything, and the people that should keep quiet, please just shut it. They aren't helping with the situation.
All that just because he was being nice to his blind cousin...