Basic Trope: A Housewife has an affair with service personell that visit the house. Compare Pizza Boy Special Delivery, with the added implication of an ongoing illicit relationship (rather than a one-time fling).
Straight: Alice has sex with the milkman while Bob goes to work.
Exaggerated: Alice has had sex with the milkman, the mailman, the gardener, the ant exterminator, the poolboy andthe maid while Bob was at work.
Downplayed: Alice flirts heavily with the milkman, but it doesn't go beyond that.
Alice is unhappy in her marriage, and any one of these people give Alice more attention than Bob does.