My wife and I have been together for many years and that, to me, is like endlessly fascinating and endlessly confusing how to sustain all of the excitement from the front of our relationship, valuing that versus the comfort and knowing that she knows all of my flaws and still loves me. It's great, but certainly not as exciting as it was day one.
My wife and I are like twins and that is a great and a terrible thing for a marriage. It makes for the most comfortable thing in the world to be truly known and loved, but also makes for a lot of conflict and that's how we roll in my house.