In just a few words, this short poem sets up a puzzle. The speaker climbs the stairs in the morning, apparently heading toward a fight with his wife. But the last line, "the tang of peace," turns that expectation upside down.
The key is the word "outcome." It suggests the poem is about what a quarrel leads to, and the answer seems to be peace rather than damage. "Tang" is a sharp, almost bracing taste or smell, so this isn't a soft, sleepy calm. It's peace with an edge, the kind that comes after something has been said out loud and cleared away. The phrase "to war" may also be half-playful, a way of treating a small domestic disagreement with mock seriousness.
The mood is wry, intimate and quietly affectionate. The speaker seems to feel that conflict and closeness belong together in a marriage, and that the argument is part of how the two stay at ease with each other.