Then do you support outlawing marriage for couples who are sterile?
Society rewards the institution not the individual.
Even a nonproducing couple promotes the institution of marriage. (as aunt and uncle, grandmother and grandfather, as step father and step mother) It is the model promoted for producing subsequent generations.
Homosexuality exists only for recreational sex.
As a matter of history, a marriage was annuled when no sex act that would produce a child was performed, consumating the marriage. Homosexuality is likewise a nulity.
A normal couple that adopts fits the model of mother and father and the child need never know they are adopted. Children adopted in states where homosexual adoption is still legal are ALWAYS part of an abnormal sexual lifestyle based only on recreational sex.
So to answer your red hearing, homosexual advocacy argument, a man and woman who marry and never produce children do deserve reward from society because their marriage bolsters the institution of marriage.
How would it be determined whether a person who wanted to get married is sterile or not?