This TED talk may help explain why the lifestyle is so appealing to us:
The take away quote is:
Millions of years ago, we evolved three basic drives: a sex drive, romantic love, and attachment to a long-term partner. These circuits are deeply embedded in the human brain.
These are independent drives. They are complimentary and at times contradictory. I find it may just explain a lot of things.
I found this via Justin J. Lehmiller.