There is another scene where one of the sisters is told she should consider marrying an older man, and that it is wrong to marry for love or looks (or, in a modern sense, base a relationship on "sexual attractiveness -- I recall those therapeutic discussions in NYC from the 1970s). In their culture, you needed to "have" a marriage, which made many moral questions two-way streets.
There are references to “low ideals”. Andrei later says, if he had life to live over, he wouldn’t marry. After tragedy, the sisters sit on the porch, with a sunset behind them, and say they just go on living.