... may investmaterial and social resources in her, such as by buyingher gifts, paying for her food and entertainment, spend-ing time with her, and declaring himself willing tocommit to having ... assumes that in each social interaction, eachperson gives something to the other and gains some-thing from the other (hence the exchange). The valueof what is gained and exchanged depends in part ... couples within a social systemwill be meaningfully interlinked and organized. Like social exchange theory itself, the exchange theory ofsex draws on economic theory and its understanding ofmarketplace...