Unpopular opinion, but I don’t like the painter friend.
People might say that the ML knew about the act MC put up but didn’t do anything but that was because he thought the reason she did it was because she didn’t like him. However nobody brings up the fact that the painter knew ML loved MC from the beginning but never told MC apparently his best friend and the only woman he lived despite knowing how much it hurt her that she thought he didn’t. And although ML seems dumb in this story, I don’t believe there’s anyone that can deny that MC is also equally dumb, cousin is dumb, butler is understandable (there was social barrier between him and cousin). So for me Claude (painter) supporting MC and wanting ML to hurt doesn’t seem as anything besides biased judgement, especially after he confessed his love for a married woman going through troubled times at that. That just made me lose respect for that character.