"Mistakes have consequences, but they shouldn’t tank our joy for each other in the long run."
I know—I totally scored getting an easygoing partner. But during often-literally-crap-filled times, couples have a choice: We can blame the other person for the unpleasant situation in which we find ourselves, or we can solve the problem at hand. When we dwell on mistakes, the stress can linger and set the tone for the rest of the day. So after we've figured out a solution, realized that we're safe, and that like most things, This too shall pass, we'll announce our favorite phrase: "Making a memory!"
This is not to say that we are a perfect couple without tensions or problems—making a memory doesn't solve everything. But it does redirect the frustration from one another onto getting through the unpleasantness at hand. This is true even when someone is "at fault."
I didn't write this but assume most couple who learn to live together get this. The bad times will come and you can either work them out together or tear up the relationship.