Far From the Mading Crowd by Henry Hardy

Hardy fell in love with or met someone called Florence Dugdale in 1906. She came to visit him, she was an admirer and they had various holidays together without Emma knowing. By 1910 Hardy wanted Florence to have a sort of larger role in his life as relations with Emma were very bad. He engineered this meeting between Florence and Emma at the Lyceum Club in London which led to what is more or less a menage artoir. It all boils over on Christmas day of 1910 when Hardy wants Florence to come with him to visit his siblings and Emma says no they will poison you against me. But in a very weird way after Emma dies Hardy falls in love with her all over