Anna Karenina Part 3, Chapters 7-11
Dolly and her children move to the family estate to cut down on some financial expenditures and get a rest from the city life. The estate is located right near Levin's. Dolly comes to the countryside to regain her stability and find happiness with her kids. She succeeds.
Kitty is coming for a visit to Dolly's estate. Levin says he will make himself unavailable, since he is trying desperately to forget Kitty. Yet once Kitty arrives, Levin spots her in her carriage and their eyes meet. He realizes he still loves her.
"He could not be mistaken. There were no other eyes like those in the world. There was only one creature in the world who could concentrate for him all the brightness and meaning of life. It was she. It was Kitty." Part 3, Chapter 12, pg. 293
Levin again realizes his most sincere feelings are stemming from his heart, not his brain. There is no time to analyze; his heart has told him what he needs to do. Incidentally, right before he sees Kitty, Levin meets a young married couple who are very much in love. He realizes that the harmony and synchronicity they share is exactly what he is missing in his life. Not coincidentally, this is what he anticipates with Kitty.