The speaker begins by wishing to be a butterfly, something beautiful and admired, and quickly turns to a quieter idea: butterflies only notice people when they're happy. Moths are different. They show up when we're crying, or when we're alone at three in the morning and falling apart. The speaker imagines the moths saying "I'm here for you, I know how you feel," and believes they can say it because they've been through the same thing.
The poem then pulls this into a simple pairing. Moths are the sad side of butterflies, butterflies are the happy side of moths, and people sit somewhere in between. The mood is lonely but gentle. The speaker seems to want someone who understands pain without having to explain it, and finds that comfort in an image from nature. The title, with its discarded supermarket flowers, suggests a low moment, though the poem itself never says what happened. It ends on acceptance rather than despair: sadness and happiness are two sides of the same creature.