In the middle of the chapter I was thinking that Fei Yue is really kind and never envy all the third princess's husband. And then when he burn Bai Yu letter, I'm changing my mind. Maybe Fei Yue treated all the princess's husband with kindness to get attention from the princess, or to deceive them that he wasn't an enemy. And then I remembered some quotes from another manga that said; "All humans are self egoistic creatures, and it isn't unusual for them to have some hidden intentions."
Well, they got me in the first half, ngl.