I have found that if you're married 10, 15, 20 years, you've reached a state that some call comfort and others call boredom.
So what exactly is the difference and what happens next? In my opinion, the difference is not in the marriages but in how the partners view life. The people who are bored are people who have a high threshold for fun, excitement and change. The people who are content, and are set and comfortable, are people who like stability, do not require a tremendous amount of newness or change and like to have the same meal schedule every week.
I find myself in the first category. I have a high threshold for fun and excitement, I NEED and crave change and I have never had a meal schedule. My husband on the other hand, is the polar opposite. He is all about stability, hates change and would LOVE!!! a consistent meal schedule (he has yet to ever get one from me.)