We can pair this with the previous chapter. (Part 3, ch.2 and this one — ch.3) Mariya and Pierre both decide to “go with the flow” when faced with their own conflicting emotions. Brian E. Denton identified Pierre’s fatalism as bogus — because he could have intervened himself one way or the other.
Mariya by contrast seems to be genuinely powerless in the question of whether, and to whom, she will get married. In a way, Mariya’s position is not fatalism at all because we get the impression she really doesn’t have a choice…Or maybe that’s what makes her a true fatalist. She can’t believe that a change of dress might swing chance in her favour.