Performance is set at home before it is tested in public.
The research on married workers is unusually consistent: the quality of a marriage spills into work, and the influence runs more strongly from home to job than the reverse. A twelve-year national panel found that rising marital satisfaction tracked rising job satisfaction, while rising marital discord tracked decline, and that marital quality was the more influential of the two domains.
A five-year Washington University study of 4,544 married adults went further. Having a conscientious spouse predicted higher income, more promotions and greater job satisfaction, regardless of gender and after accounting for the worker's own personality. The mechanism was not that partners did the work; it was that they created the conditions to work effectively. Newer research on spouses' emotion-regulation skill finds the same crossover into stronger relationships with supervisors and better career outcomes.
For a politician, working effectively means absorbing attacks without absorbing their poison, making decisions on four hours of sleep, and showing up the same person on Thursday that voters met on Monday. That capacity is replenished or depleted at the kitchen table.