He created them together, right at the beginning of humanity. He did that because sex and marriage go together for a reason. Sex is not an expression of just any kind of love. It is an expression of permanent, exclusive, self-giving love between a man and a woman. Married sexual love is the kind of love which is the foundation of a family.
Sexual intercourse is, by definition, an act that occurs between a man and a woman.
If you know anything about biology, you know that the parts are designed to work together. In joining together, a man and a woman complete each other. They become one. The man gives of himself, the woman receives. That does not happen in homosexual activity.