Melvyn Douglas' wife is divorcing him, and he meets Ruth Hussey on a boat. Ruth is very cold and controlled throughout the movie, and I couldn't figure out what he saw in her. He was still married to Ellen Drew, who wanted a divorce. Melvyn moves Ruth and her family in his house, and when Ellen returns, deciding she didn't want the divorce after all, Ruth refuses to leave, even though good manners and a sense of decency would dictate she should. (After all, since Ellen was divorcing Melvyn and not the other way around, he probably didn't want the divorce in the first place, and Ruth would just be a 'rebound'). If Melvyn still wants to leave Ellen, he should do it with Ruth not there, because that's the only way she'd really know. But he was never given the chance, and the writers did everything they could to make Ellen look like a terrible person, but all it did was make her look like a woman trying to hold her marriage together. Ruth should have figured out that if he didn't leave his wife then, he probably never would have. So, in order to prove Ellen can walk, Ruth sets his house on fire (hoping Ellen will flee). Melvyn's decision ultimately is, does he stay with Ellen or go with a psycho who can't think of anything except to set his house on fire. In the end, we still don't know if he did or not. It left you hanging.....