from page 611-612 of original text
page 485-487 Pevear/Volokhonsky translation
"In the middle of summer, Princess Marya received an unexpected letter from Prince Andrei in Switzerland, with a strange and unexpected piece of news. Prince Andrei announced his engagement to Miss Rostov."
This is a major point in the story... there will be huge ramifications in a number of lives; but these pages mostly underline what we already know of Marya, her passionate religious longings and the conflict she felt between her longing to devote her life to worship, and her devotion to nephew and her father (in spite of the old Count's constant scorn). In some twisted way, she's the ultimate martyr.