Beth, you are so, so right in what you've said.
When I think over the nearly 22 years I've been with my wife, I can chalk it up to having come in 'phases', and some of those phases (which is comprised of several years apiece) were NOT good and almost led to separation.
But we loved each other and knew we wanted to work it out and we did.
This last phase (the one we're currently in) has been the absolute best phase ever. We know each other so well that communication is much, much easier and occurs without even consciously trying to do it.
It's truly like a roller coaster, where the last stretch of it is when it smooths out and you feel the relief of not having those huge peaks and valleys.