nail on head.
it is a sexual perversion and nothing else.
If it is about love and nothing else as they say then why the need to have sex.
I love my family and dog but I feel no need to have sex with them just my wife and why is that?
Because I am attracted to her sexually.
Two men and one has to pretend to be the woman, two women and one has to pretend to be a man and wear a strap on. and then they say they are normal for crying out loud.
It is all based on sexual perversion and nothing else.
You are right. The reason for the sexual bond in heterosexual marriage is for the protection of women and the children. Throughout caveman days, if a woman had no male protection, she and her children would die.
For survival, the societies that practiced marriage and monogamy (Jews and Christians) flourished while other pagan or muslim or Hindus or marxist cultures could never create stability (the trust and healthy children that starts in two parent families) and thus an atmosphere for freedom, invention, commerce and creativity.