Two short lines carry a whole relationship here. The speaker says that as long as "you" keep breathing, they themselves won't be able to. Taken literally, that's impossible, since one person's breath doesn't cancel out another's. That gap between the literal and the felt is where the poem lives.
The title, "Suffocation," tells us how to read it. The speaker feels smothered by this other person, whether through love, fear, guilt, or a painful closeness. The poem doesn't say which, and that openness is part of its power. It could be an overwhelming attachment, or a bond that has turned toxic, or even a wish that the other person would simply go away. Judging by the wording, the feeling is desperate rather than calm.
The mood is tense and airless. Lowercase letters and the abrupt ending, which stops on "to" without finishing the thought, mimic someone running out of breath. The poem itself seems to suffocate.