此花已有主本主已有花
[cĭ huā yĭ yŏu zhŭ bĕn zhŭ yĭ yŏu huā]
This implies that 'this flower has an owner and the owner already has a flower'. It metaphorically suggests that one’s affection or interest has found its match or home, often used by someone who feels they are taken or unavailable for romantic interest.