A misalliance - Anita Brookner

After twenty years of marriage Blanche Vernon is alone; abandoned by her husband Bertie for a childishly demanding computer expert named Mousie. While Blanche finds this turn of events baffling, she feels that Bertie must have left her because of her overly sensible demeanor. Yet many of their mutual friends disagree. In fact, Blanche has come to be regarded as undeniably eccentric--making elliptical remarks that no one knows how to read, and chatting at great length about characters in fiction. She resolutely fills her unwanted hours with activities, maintaining her excellent appearance, drinking increasingly more wine, and, in an attempt to turn her energy to good works, becoming severely enmeshed in the life of a disordered young family.