When the book opens up, Henry Lee's wife, Ethel, is already dead. Still, she definitely leaves an imprint on the lives of her family members—Henry and Marty are having a hard time with her absence, and they miss and love her terribly. Figuring out how to come together after her death is part of their shared struggle in this book.
On the flip side, Ethel is also the reason that Henry has never sought Keiko out; he loves his wife and doesn't want to betray her in any way. With Ethel dead now, though, he can finally embark on the next chapter of his life and find his first love again. He knows Ethel would want him to do this because she's always wanted him to be happy, so without any guilt, Henry reconnects with Keiko.