Each pair of lines in this poem works as a mask and what lies behind it. The capitalized lines are the things the speaker says out loud: "I'm fine," "I'm just tired," "Go away." The lowercase lines underneath are what they actually feel. The gap between the two is the whole point. Someone says they already ate, and the truth is that they are starving themselves. Someone says they're just cold, and the truth is that they are hiding scars.
The speaker seems caught between wanting to be left alone and desperately wanting someone to notice. "Go away" is answered right away by "show me you care enough to stay," which suggests the pushing away is a test. The mood is quiet but heavy, and it gets worse as the poem goes on, ending with "I'm okay" beside "I just want to die." The final pairing is the most painful because the lie sounds the most casual. The poem shows how ordinary phrases can cover real pain, and how easy it is to miss.