At the Oceana Apartments, he keeps in his desk a letter to Lois Neilson, his ex-wife, a letter he writes and rewrites but never sends. He and Lois still see each other occasionally, because of their daughter. Too many years have gone by for them to remain angry at each other.
He cannot say why the letter remains unfinished, and therefore unsent. It may be that Lois already knows everything it contains. If so, then he is writing it not for her but for himself. It is an ongoing conversation with his grief.
The substance of the letter, in all its forms, is the same. Only the words change. It tells Lois Neilson that he thinks of her with fondness. It tells her that no day goes by without some small remembrance of their son. It tells her that he has imagined many different lives for their lost child, but in each the boy is happy.
It tells her that he is sorry.