Yeah, I think the term is really "integrate". While I'm not dependent on my wife, there are things that I trust her to do and things she trust me to do, and we don't even think about them anymore because my partner is handling them. You give up stuff because your partner has got them. You sort of sag into each-other as people.

"And the two shall become one flesh."

I thought that was a reference to the joining of the DNA in the progeny.

Like many things, it can probably be read multiple ways.

Yours is an interesting reading, and I must confess it had not occurred to me before.

Stephen Covey used[0] the term "interdependent", which I rather like.

[0] 7 Habits of Highly Effective People