Fengyou probably never thought that Fuying never thought about betrayal, or that the two of them had different understandings of betrayal from the beginning.
It starts with a play and ends with a play. No one can tell clearly who is right and who is wrong. Even after everything happened and ended, there was still no way to explain it clearly. In the end, the sentence "Each one is his own master" explained everything and ended it by the way.