[joaonmatos]

You make a very wide set of assumptions about some kind of metaphysical complementarity inside a couple that erases homosexuality and presupposes some naturally ordained monogamy.

I am sorry, but unless you substantiate it in anthropological terms, it is utterly unfalsifiable and the argument should be thrown out in its entirety.

The lived experiences of many queer and polyamorous people, plus the evidence of "deviant" behaviours in many animal species and historical and present societies contradicts your prescriptions.

[midoridensha]

There's nothing natural about monogamy. Humans only practiced it after agriculture became widespread and the idea of land ownership became important. In tribal hunter-gatherer societies, children were raised by the tribe and not just their parents, and who the father was wasn't considered important.