he had an idea-too sentimental to speak aloud and he knew none of his divorced friends would ever own up to it-that something must linger, a half-life of marriage, some sense memory of love even if obviously not the thing itself. He thought these people must mean something to one another, even if they didn't like one another anymore.
The character reflects on the remnants of past relationships, particularly in the context of divorce. He considers the lingering feelings that might persist despite the end of romantic ties. There's an acknowledgment that even when love fades, a form of emotional connection often remains, though it's seldom discussed openly among friends who have experienced similar separations.
This notion of a "half-life of marriage" suggests that shared experiences between people leave a lasting impression, implying they still hold significance in each other's lives. The individuals, despite not harboring romantic feelings anymore, may have a unique bond shaped by their history together, indicating that emotional ties can endure beyond the end of a relationship.