The title "Instrumental" does three jobs at once. It names a musical instrument, it means being the means by which something happens, and it describes music without words. All three meanings suit a poem of eight short lines about a man who doubts his own music and then finds, almost against his will, that it has worked.
The opening couplet is modest on purpose: "an ordinary husband may sing / tuning his guitar." The word "ordinary" shrinks the speaker before he has even appeared, and "may" makes singing a possibility rather than a performance. The man is tuning, not playing, which is the moment before music, when sound is still rough and nobody is really listening. With no punctuation, "may sing" and "tuning" slide together, so the singing seems to happen inside the preparation.
Then the poem switches to "I": "I play a bad instrument / with rich oils." The phrase "bad instrument" is blunt, almost childlike, and it collides with the lavish "rich oils." You do not normally play an instrument with oils. You polish it with them, or anoint something, or paint, or massage. The poem never says what the instrument is. Judging by the imagery, it may not be the guitar at all but the speaker himself, his body or his voice. Whatever it is, the pairing sets a poor tool against generous materials, as if modest talent were being treated with great care. That gap invites the reader to fill it.
The third couplet is the poem's moment of nerves: "I dare not believe it is good / better than expected." "Dare not believe" belongs to the language of faith and superstition, as though hope itself could be jinxed. The line break does quiet work too. He reaches for the word "good," and the next line retreats to the hedged "better than expected." That is a self-correction in miniature, a man lowering his claim before anyone can lower it for him. It is faintly comic, but it also feels honest. He wants the praise too much to say so outright.
The answer arrives in the last couplet, and it comes from someone else: "and my love is dancing / in her bed." The small word "and" suggests cause and effect without explaining anything. "My love" can mean the beloved or the feeling itself, and the line holds both. The pronoun then shifts from "my" to "her," so the bed belongs to her, and the speaker seems to be watching the result with some wonder rather than claiming credit. "Dancing" is the first word that shows music working, not just hoping to. Nobody in the poem says the playing was good. The only evidence is her movement, and that is what makes the speaker "instrumental" in the best sense. He is the means of her pleasure, not its judge.
The form supports this gentleness. There is no rhyme, no punctuation, and no capital letter except the lone "I." Each couplet pairs a longer line with a shorter one: "I play a bad instrument" is followed by the three-beat "with rich oils," and the poem ends on the shortest line of all, "in her bed." It lands like a final soft note, or a door quietly closing. In place of rhyme there is a faint chime of -ing words (sing, tuning, dancing), which carries the idea of ongoing, unfinished music from the first couplet to the last. Even the sounds are casual, not polished.
What makes the poem worth reading is how much it trusts understatement. It could have boasted about desire or talent, and instead it admits uncertainty and lets someone else's joy settle the question. Its quiet claim is that love does not depend on skill, and that a "bad instrument," played with enough care, can still make someone dance.