Catholics come close to saying that marrige for anything other then the purpose of having children is wrong. It is a fundamental tenet of the Catholic faith that the primary function of marriage is having and raising children. The social and other functions of a marriage are secondary.

Also, the Catholic church does say that impotent/infertile people can not get married. Currently the Catholic church only enforces that rule when physical imparement prevents consumation of the marriage, but in the past they have read it far more broadly. I believe the religious term in "dire impediment", it's a list of things that prevent a marriage from being valid. Most of them are sensible things like forcing somebody to say the vows or already being married.

Jay