Chapman is a pastor and marriage counselor who had an insight that there are multiple ways of expressing love, and turned it into a small self-help empire.

The five love languages are words of affirmation, quality time, receiving gifts, acts of service, and physical touch. In Chapman's analysis, relationships start with couples falling in love, and this mutual infatuation leads to a stage where people tend to speak all of the love languages at once. As people settle into a stable relationship, this tends to fall off. The problem is when one partner's expressive love language isn't the same as the other partner's receptive love language. Then you have couples saying "Well, I do XYZ, but they don't really love me." And if your love tank run outs, a relationship falters.

One of Murphy's Laws, "If it's stupid and it works, it isn't stupid." Love languages is a lot less sophisticated than Esther Perel's psychodynamics of intimacy and desire, but it also explains why when my wife lets her discarded shoes pile up around the living room and forgets to put cereal back in the pantry it feels like a personal attack. Chapman ascribes near miraculous powers to love languages, fixing marriages most people would have bailed on. For what it's worth, Chapman is rather churchy and traditional in his approach to gender roles, but I think the underlying ideas hold regardless.