Seven years, two kids later here. Better every year, no joke. Invest in the relationship by giving a fuck, don’t just assume a zero maintenance or poorly attended relationship is going to stay cool. Repay her occasional poor attitude with grace and love, and hope that she will respond by cutting you slack when you wind up being an asshole from time to time. Give and take, and intentionally learn to love with acts, not depending on emotions to make it through. Actions generate emotions, not the other way around.
Probably the single best comment on Reddit I have ever read, especially since I can directly relate.