You should tell him then if he’s tired of you overthinking then maybe he needs to start doing things to make you feel more comfortable. I’ve had this problem with past relationships so I’ve made it very clear in my current relationship that i like reassurance. But you should also just be straight up and say: “I’m not overthinking, i can tell that you’ve genuinely been more distant since the argument. And i would like to figure out what’s wrong so we can work through it”