I think you hit on an important basic of relationships - long term in particular.
I think it's easy with all the pressures of day-to-day life to let the focus slip off the relationship. We call it "getting in a rut". And we've learned over the years that the best way to deal with it is just push the "Rut Alarm" button. Either of us ! Then we step back, take a deep breath and refocus on "us" and not so much all the other crap that's coming at us. It's good practice because it WILL happen again ! Mount that alarm button right in the kitchen ! Unless we can go back deep into a cave in the mountains where there's nobody but us to focus on.
And yes - isn't that great when you do refocus and become even closer ! One of the majik things