People with ADHD tend to lose negotiations they should win. Not because the ask is unreasonable — the accommodation, the extension, the later curfew, the raise, the split of the household work is often entirely fair — but because of how the ask arrives: unprepared, urgent, all at once, and attached to six years of grievance. The other side stops evaluating the request and starts defending itself. A fair ask gets a no, resentment rises on both sides, and the next conversation starts from further back.
That holds for a twenty-two-year-old asking his parents to cover insurance one more year, an adult asking a manager for a modified schedule or a spouse for a different division of labor, and a parent trying to reach terms with an adult child still at home. Same rules in every direction.