Every time Denethor rides out to inspect the fortifications or rally the troops, some part of Finduilas is certain that this will be the last time she sees her husband alive. But she refuses to dwell on the possibility that he will leave her a widow, their sons fatherless, and Gondor without a Steward.
She has too much to do, though her responsibilities terrify her. In her husband's absence, she is the commander of Minas Tirith's garrison, the leader of its defenses, its final arbiter of disputes.
While Denethor is in the field, she is Steward in all but name.