The widower's tale / Julia Glass.

Enhanced descriptions from Syndetics:

In a historic farmhouse outside Boston, seventy-year-old Percy Darling is settling happily into retirement: reading novels, watching old movies, and swimming naked in his pond. His routines are disrupted, however, when he is persuaded to let a locally beloved preschool take over his barn. As Percy sees his rural refuge overrun by children, parents, and teachers, he must reexamine the solitary life he has made in the three decades since the sudden death of his wife. No longer can he remain aloof from his community, his two grown daughters, or, to his shock, the precarious joy of falling in love.
nbsp;
One relationship Percy treasures is the bond with his oldest grandchild, Robert, a premed student at Harvard. Robert has long assumed he will follow in the footsteps of his mother, a prominent physician, but he begins to question his ambitions when confronted by a charismatic roommate who preaches--and begins to practice--an extreme form of ecological activism, targeting Boston's most affluent suburbs.
nbsp;
Meanwhile, two other men become fatefully involved with Percy and Robert: Ira, a gay teacher at the preschool, and Celestino, a Guatemalan gardener who works for Percy's neighbor, each one striving to overcome a sense of personal exile. Choices made by all four men, as well as by the women around them, collide forcefully on one lovely spring evening, upending everyone's lives, but none more radically than Percy's.
nbsp;
With equal parts affection and satire, Julia Glass spins a captivating tale about the loyalties, rivalries, and secrets of a very particular family. Yet again, she plumbs the human heart brilliantly, dramatically, and movingly.