Love is the only thing that matters because it ain't a feeling. A variety of feelings accompany it, and they can and do change from time to time.
Love is the acceptance of responsibility for a relationship. There is some truth in the evolutionary causalities you mentioned, bro, but that's not the last word.
Lust, infaturation, addiction to the body's own brain chemicals, they are a factor as well.
Marriage has never been about women needing men for their strength. Marriage has always been about the children, really. Yes, even for those who for one reason or another can't have them...don't get the cart before the horse.
Marriage is an institution that was really created by God to give us the opportunity to become more like him...and to become closer to him. Love is the path and the experience and the price we pay for that transformation. And it ain't always pretty.
It's simply another opportunity for to lose ourselves in order to find ourselves. The problem is that too many people lose themselves in things that don't return anything at all in the end, much less self-discovery or transformation.
If you can simply live by the premise that it's all about being the right person...not for your spouse, or even your kids, but for the One who created you, things will happen that you simply cannot believe right now.
You keep using that word. I do not think it means what you think it means. -- Inigo Montoya, 'The Princess Bride'
