My writing of this part in the novel was broken up by a trip out of town for work, so my recollection is less clear. It's feeling to me like this book can be split in two--building towards Anna and Vronsky's affair and its aftermath. I keep wanting to describe the novel lately as fallout. However, in this part, where we see Vronsky and Anna abroad, Karenin on his own, we also see Kitty and Levin finally marrying. As one set of relationships becomes ever rockier and unstable, another begins (though not without instability).
My favorite bits here concern Kitty and Levin's wedding and adjusting to one another in their marriage, including the death of Levin's brother (completely awful and real).