Living with your partner is hard. You have your emotional and physical things, your partner has his or her emotional and physical things, and enough of the all these things need to find a way to be compatible or the co-existing experiment fails. That’s hard stuff dude.
You know what else is that hard? Making sure there are the correct number of marshmallows in a box of cereal. If after the third count I confirm that I don’t have all the marshmallows I was promised I write a very stern letter. Very. Stern.