Characters
Marriages don't break up on account of infidelity. It's just a symptom that something else is wrong.
— Jess · When Harry Met Sally...
Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The speaker distinguishes a visible sign of marital trouble from its underlying cause. In this account, infidelity reveals that something else is wrong rather than explaining the breakdown by itself. The claim redirects attention from one act toward difficulties already present in the relationship.
Context reviewed