The romance genre is filled with happily ever afters - they are what romance is all about. On some level I think everyone craves a happily ever after.
The lost dog finds his way home,
the world is saved,
or the couple in love works everything out.
Real life sucks. Reality is hard and we all hope that someday all the strife and hard work and sometimes the general nastiness of real life will be rewarded by our own happily ever after.
If a book ends and it's not a happily ever after it leaves me feeling unsettled. That's probably why cliffhangers annoy me and my OCD tendencies - everything should fall into place just like I want it.
That's why I like a HEA. Why do you?