The similarity, “not their gender difference, was what made them suitable partners.”
Very well nuanced. Thought-provoking. You only have so much space. I am curious as to how you treat the significance of the body and its sexual differences in genital intimacy. It seems to me that JP's ToB is asserting that the body, and its design matters. And that it expresses something in the sacrament of marriage that cannot be expressed in other relationships. It may be, that if there is any substantial or significant difference in SSM marriage vs. M-F marriage, this is it. Otherwise, friendship can be described in non-physical terms, even gnostic in contrast to the affirmation of materiality, which the Incarnation brought to us. I can't adequately express my question here. It just seems that conjugal coitus differentiates marriage from all other friendships and partnerships, and that "traditional" marriage serves a public social purpose (procreation and socialization) that more private relationships do not, whatever their contributions to the common good.
One possible typo - did you mean to say "Aquinas" in the sentence below instead of Augustine?
"Second, Augustine states that there seems to be this friendship, not simply because the two are married, but because of their “partnership of the whole range of domestic activity,” in addition to the “gentle association” produced by the “act of fleshly union.”"
Fascinating treatment. I had never noticed that the definition of marriage in the Church seems to have progressed to include the end of "the good of the spouses." I look forward to reading part 2.