Most people desire to have a romantic relationship, and most people desire to have a child. The paper suggests one respect in which it is more desirable to have a child with a romantic partner rather than with someone other than a romantic partner, as platonic parents do. The first premise claims that the romantic relationship, and only this relationship, has a certain desire as a constitutive part. This is the desire to be as related to someone as one can (...) be. That this ‘desire for relatedness’ is a constitutive part of the romantic relationship explains why those related by a romantic relationship tend to become related in other ways and explains why romantic partners tend to desire to have relationships with those to whom their romantic partner is otherwise related. The second premise is that by having a child together romantic partners become related in an important and unique way, satisfying their desire for relatedness. Since platonic parents do not have the desire for relatedness toward one another they do not satisfy such a desire in having a child together. A brief review of the sociological literature on platonic parenting is included and eight objections are answered. (shrink)