Why is Salzman mourning when his daughter and Leo fall in love in "The Magic Barrel?
Salzman is mourning when his daughter Stella and Leo fall in love because Stella is "a wild one - wild, without shame." Stella has apparently committed an act of depravation so grave that her father has disowned her. In Jewish tradition, when a child has done something as grievous as Stella has, she is considered dead to her parents, which is why Salzman is reciting the Kaddish, or prayer for the dead, when he sees her. Salzman has warned Leo not to bother with his daughter, as, in his estimation, she is beyond redemption, "not a bride for a rabbi."Leo suspects, however, that Salzman, who is quite a crafty salesman, has engineered for him to have seen Stella's picture and fallen in love with her, and if this is true, then the old man sees a relationship with Leo as a last chance for his daughter, because, as he tells Leo, "if you can love her, then you can love anybody."
Redemption comes through love, but evil is a formidable opponent. Leo, newly come to the understanding of the power of love, believes that he can love Stella and "convert her to goodness," but the success of his endeavor is, for now at least, questionable. Although it is possible to interpret the ending as being hopeful and happy, what happens after Leo and Stella meet is not definitive. I believe that an alternate interpretation might be to view Salzman's mourning as a portent, that love will not be enough to overcome the evil in Stella, and that the result of their union might spell a figurative death for them both.