In the eyes of the state, they legally valid.  When I was in Catholic HS sacraments class, as well as pre-cana, we were taught that the couple performed the sacrament and the priest was witness.  If you check canon law, it will say that fecundity is not the requirement for marriage, only the ability to have sex.  You may not like their sexuality, but that is because you are not gay.  Sex is still a gift from God.  Homosexuality is not disordered if you include being born gay as part of the natural order due to epigenesis.   Of course, to understand any of this, you must place reality over authority.