True Love
In the modern global West it is supposed that stable human mating bonds are based on something called true love. "You are the love of my life, my One True Love", say boy and girl to one another.
Popular entertainment expresses this myth in a pure form.
Real life may be less naive, but whenever boys meets girl the myth usually lurks nearby.
"True love" is a myth, a misleading extrapolation from the phenomenon of infatuation, of being in love. Being in love is generally a transient experience, as people fall out of love almost as readily as they fall in, so bonds based on it are unstable. One lover soon deserts the other, only to resume the quest for the perfect partner.
This myth arose recently. It developed from the courtly love of medieval Romance literature, and reached maturity in the 19th-century Neoromantic movement, which is why it is sometimes called romantic love or simply romance.
This myth is peculiar to the modern West. Societies have always been aware of the strength of infatuation, and have sometimes tolerated it, as in India's Gandharva marriages, but have usually regarded it as at least potentially problematical, a threat to order, a path to woe not to weal. I think they were right.
"True love" is idolatry, misdirected reverence, a poor substitute for the sublime love for God which reverence should be. It arose to fill the gap left by the rise of Atheism.
(How the Defection (maybe) Came About. Near the beginning Yahweh made Eve. At least that's what Adam called her, but she wasn't having any of that! "Who are you to pin your labels on me? Our maker did not bother to give me a name (unlike some folk I could mention) so I think I'll choose my own, thank you very much!" And Yahweh said "I gave you to Adam so you were his to name". Eve was not impressed. "But I don't love him in that way. I love him as a brother of course (despite all the annoying habits he seems to have developed in the few hours since you made us), but surely I should follow my heart, and give myself to the man I fall in love with! Or (for I realise that my choise is rather ... er ... limited) remain single, if nobody turns up whom I fancy. But surely you can make a better man than Adam if you really try! You know what they say: practice makes perfect, and if at first you don't succeed, try, try and try again! (Well, I suppose they don't say it yet, but I'm sure they will.)")