Love. Separate from desire, as, I suppose is generally agreed upon. Shakespeare of course had an opinion: "Love is not love which alters when it alteration finds, or bends with the remover to remove. Oh no it is the star to every wandering bark."* What "star"? Just off the top of my head, the most durable marriages I've observed were grounded in religion. Yeah, that "star."
So many divorces. Oh the divorces I have seen. Luckily I know none where there were children. Except my own, unwanted divorces, two. Dreadful for children, catastrophic in fact. The kids think they were to blame, the little innocent darlings.
It's astounding how skillful some people can be in talking themselves into believing they are no longer in love. A common self-deception is for someone in an illicit relationship, unfaithful, and out of terror at being found out, convince themselves that if they were REALLY in love they wouldn't have done it, wouldn't have had that tryst in the back seat of a parked car in the darker recesses of a parking garage, love to the accompaniment of squealing tires as cars go from floor to floor.
Grubby. Life can be so grubby. I suppose the fragility of love is sometimes what drives people to escapes such as drink, gambling, drugs, food, honing ones skills at lying, always having a backup lover in their secret cache of phone numbers.
For all of those reasons, and millions more, writers of fiction can potentially have a ball writing about the vicissitudes of Love. One excellent defense against the fear of loss of love, is to love God more. Who's that strong however?
Barry
* From Memory I've left out a clause I can't remember.