A comment here:
I do find this whole "one flesh" kerfuffle a bit unsettling. The term is not QUITE an accurate translation, IMHO, of the original Hebrew.
The term is more literally, "flesh echad." And, again, the translation is not literally inaccurate, but flawed. Because 'achat' or 'echad' (depending on the noun gender) can mean the cardinal number "one" - but is often, depending on context, something "bigger."
It more generally means "a UNITY." A "flock" is, for example, "echad." The people (ha-am) of "kol Israel," started out in the wilderness as a 'mixed multitude,' of twelve tribes plus, but - at least briefly - eventually became a people who were 'echad.' Ezekiel's famous "two sticks" (chapter 37) became "echad" in his hand. And, vitally importantly, in Deuteronomy 6:4+ (which the Messiah Himself said clearly is "the Most Important Commandment in His Book) that "Shema, Israel...YHVH Elohenu, YHVH Echad..."
Yes, we've all heard it rendered, with the Name omitted, that He "is One." But, then that refutes the whole "trinity" thing, and results in knock-down, drag outs. (I have often said that I can related to trig, differential equations, and integral calculus, but have trouble understanding "3=1")
The point is, He is a Unity, arguably, even "All."
So, I contend, to repeat, that "echad" means more than just a single cardinal number.
And that a husband and wife become a "flesh, echad," makes sense on so many levels. It also helps explain what Adam said Chava was "flesh of my flesh, bone of my bone," and a father, too, has a unified flesh relationship with the daughter of his own seed, at least until he chooses to transfer such.
All of which, again hearkens back to why I contend some concepts can be hard to translate, particularly into a single word in another language, without context or explanation.