NSFW - How important is sex to you in a relationship?

I wonder about other couples; I’m in a relationship of about a year and a half and wonder how important sex is to other couples. I know I shouldn’t compare, but I can’t help but wonder. I know stress has a large effect on things, but I wonder is having sex once or twice ever couple of weeks normal for a committed relationship? What happens when two people love each other, but it seems that the desire to impress the other person begins to fade? Is it just the comfort factor? I’m curious as to others experiences.