Hanahaki: Stage II
When you’re in love, flowers bloom inside you, slowly growing until they begin to protrude out of your mouth, ears, eyes, and nose. So, you are a walking flower everyone can see as the love you feel is expressed externally. Also, the one you love is capable of seeing these flowers and will choose to either love you back in return or not. The flowers go away once the love is reciprocated.
There is no logical explanation for this picture as it is quite obvious the love is unrequited. As the Hanahaki feeling progresses without requited love, the person coughs up flower petals until they die or their feelings are reciprocated. Since Hanahaki is fictional, real people cannot catch it, and hence you won’t see a lovesick man growing flowers on his body. The disease can also be cured by a surgical procedure that removes the flowers, but this will result in them losing their feelings of affection and all memories of the person they loved.