(And who says Adam and Eve were married?)
God says so and the evidence to back up that claim comes from God's own word in Genesis 2....God should know cause He was there. and infinitely so.....................
It says there that a man must cling to his wife because of the example set by Adam and Eve. But no marriage ceremony is mentioned.
What...you need an actual marriage ceremony according to whatever is in Leauki's mind?
v. 24, "Wherefore a man shall leave his father and mother, and shall cleave to his wife: and the two shall be in one flesh."
Note the words used....man shall cleave to his "wife" not woman...but wife...wife is a word indicative of being married.
So, in answer to your question, who says Adam and Eve were married....God Himself says...He was there...He inspired the writer who wrote the Book of Genesis...to use the word "wife".
It was from this moment that we can know for sure that it was God's design (making them male and female) and His plan that a man marry a woman and anything else is crazy. If you think it's not then you are entering into George Orwell land.