I've read many comments but have to say I don't think the person he wants to sleep with is his sister-in-law. You can feel that he is deeply missing and yearning someone. I think he lost the love of his life a while ago and he is at a party feeling the need to breathe clean air until he suddenly sees his lost lover's sister. He sees her as his lover's reflection but knows that they're not the same. They both carry the same pain and understand each other. He wants to be with her and get rid of his pain because she's almost just like his lost lover. But at the moment he is with someone else and he perceives their relationship as a consolation. They both know the person he's together with and they don't want to hurt that person. They're trying their best to stay away from each other and say goodbye but it doesn't change the fact that they want to be together
I've read many comments but have to say I don't think the person he wants to sleep with is his sister-in-law. You can feel that he is deeply missing and yearning someone. I think he lost the love of his life a while ago and he is at a party feeling the need to breathe clean air until he suddenly sees his lost lover's sister. He sees her as his lover's reflection but knows that they're not the same. They both carry the same pain and understand each other. He wants to be with her and get rid of his pain because she's almost just like his lost lover. But at the moment he is with someone else and he perceives their relationship as a consolation. They both know the person he's together with and they don't want to hurt that person. They're trying their best to stay away from each other and say goodbye but it doesn't change the fact that they want to be together