The speaker is worn down by a relationship with someone who says they love them. The poem opens with heaviness and a struggle to find words, and it gets more desperate from there. Even the speaker's reaction to this person is not a real smile, just a tense, involuntary twitch of the face that shows crooked teeth. It feels like something the body does on its own, not a sign of happiness.
The feeling follows the speaker through night and day until motivation disappears and even breathing becomes hard. Then the plain demand arrives: "I need this feeling to stop. / For you to stop." The line about the world being unsafe for both of them suggests the other person is struggling too, though the poem doesn't say how. The ending turns "I love you" into a trap. The unfinished sentence, "But if you really loved me," hangs before the quiet final line, "You would let me go." The mood is exhausted, tense, and sad, but also firm.