One of the core issues with ADHD is a thing called Executive Fatigue. Basically what this means is you have the ability to make only so many decisions about your life in a given day. If you run out, then you need to spend the majority of the rest of the day isolating to help your brain relax. It’s not that someone would necessarily be obsessed with the idea of an outfit, but rather it’s the idea that they had an expectation that reality has now violated. This requires further mental energy to revaluate the situation. Often times all of that energy is already spent making the plan, so when something goes wrong there is no more energy left to come up with a new plan. It’s hard to describe and many people use different words for it but common terms include “out of spoons,” “brain fog,” or “hitting a wall.”