Howard is shown to have impacted his marriage irrevocably for the worst by his infidelity with one of his colleagues. When Kiki discovers the identity of his mistress, she makes it clear that their marriage is, in anything but name, over. Howard spends the rest of the novel, rather unsuccessfully, trying to worm himself back into her good books, but this is something that other infidelities definitely do not help him achieve. His interactions with his wife, apart from one sexual encounter, point towards limited affection only. Note for example how Kiki kisses him goodby before leaving the house one evening towards the end of the book:
Shje kissed him on the cheek as Zora had, nostalgically. A reference to earlier affection.
In the same way, Howard, after making her laugh about his story about the glee club, only is met with distance. In this quote, he is hoping to be welcomed back to her bed after enjoying an intimate moment with her:
"Well," she said. Howard put his glass down on the table, ready to say something, but she was already at the doorway. She told him there was a clean sheet for the divan to be found in the upstairs closet.
Both of these quotes are important as they show how their relationship is something that lies only in the past now. In spite of Howard's attempts to restore their love, it is clear that nostalgia is all that there is left of their relationship.