I've noticed on other threads the abject confusion from BS and WS wondering about the "love" that exists in the primary relationship and the affair.
In English we use love to mean many different things: I love football. I love coke. I love George Clooney. I love my best friend. I love my spouse. True, we sometimes use words like "infatuation" or "like" but usually we toss the word "love" around.
In the ancient Greek (okay here comes my knowledge from being a preacher's kid) there were four words for what we call love.
Storge: affection (what we feel towards places or things)
Philia: friendship (what we feel for other people we care about)
Eros: sexual love (what we feel as infatuation, lust, limerance, in love)
Agape: unconditional caring (what Christians feel God has towards us, the love parents have for their children, the mature love that partners develop for each other after the eros calms down)
It seems that in our culture people don't seem to appreciate that eros must mature into agape or the relationship cannot last. Eros is not sustainable. Not to say you can't have a little eros mixed up in your relationship at times but eros won't get you through the hard times. Only agape will. It's too bad so many people don't get this.