Someone is nursing a breakup, and the speaker is trying to hide how much it hurts. The opening lines set the pattern: "I don't care" and "I'm fine" are each corrected right away as lies. The speaker admits to falling apart inside, to stealing one last glance as they walk away, and to crying into a pillow at night.
The title's "terms and conditions" works as the main image. Nobody reads them before clicking "agree," and the speaker says the same about love and life. If they had read them, they might have known that good doesn't always win, that pain is guaranteed, and that people lie. The poem then widens from one relationship to everyone: "We all lie," mostly to avoid a truth we'd rather not face.
The mood is raw and bitter, but also tired and honest. The short, blunt lines feel like someone confessing, and the final line leaves a quiet, resigned sadness.