Me, I'd volunteer to do the shopping, arrive home without the Noshu keto candy bars, say the chick she hated in school told me they're for losers and the hated chick looked amazing. Talk about US politics during her favorite shows, and include obscure, meandering, and only marginally relevant historical anecdotes about the Roman empire. Cough into the fridge, wear socks for more than one day, and pop off as soon as she starts to cum.
Always use her towel. Grunt for no reason. Make the case that blowing your nose in the sink is good for the planet and so is Donald Trump. Leave the milk on the counter but put the butter in the freezer. Bake almond croissants when she's dieting. Play the banjo.
I wish I could tell you exactly how to be an asshole who will absolutely die alone but I can only point the way.