Often the difference between a successful marriage and a mediocre one consists of leaving about three or four things a day unsaid.

Miller’s line treats marital success less as a grand romantic achievement than as a daily discipline of restraint. The “three or four things a day” suggests that conflict often arises from small, habitual irritations—remarks that may be technically true but needlessly sharp, corrective, or self-serving. By recommending that some thoughts remain unspoken, the quote elevates tact, patience, and selective silence as practical virtues that protect intimacy. It also implies that a “mediocre” marriage may not fail from major betrayals but from accumulated minor wounds. The humor of the precise number underscores a realistic, behavioral view of love: harmony is maintained by choices made repeatedly in ordinary moments.