Adam and Eve were never married. They lived in filthy, disgusting sin their whole lives. Their hot, hot sins led to children (unless God was sampling the goods before he came into Mary). Eve’s children then fornicated with each other (or their parents) (or God) (or someone) or else there wouldn’t have been any white people in Africa to write the Bible.
Anyhell, God decided people needed to get married in order to plow. He wasn’t really specific on genders because He knew gays weren’t going to be a thing if we followed His fabulous instructions to kill them. God wanted to cure jungle fever too (Deuteronomy 7:1-3, Ezra 10:2), so imagine how pissed He’ll be when He finds out modern believers are so forgiving of “life partners”. Since when is it better to love someone than kill them?