The story's title character and protagonist is a butterfly who wishes to marry a flower. Unfortunately for him, the expectations which he has of his future wife are very high. He decides that none of the flowers that he sees are worthy of being his bride. Consequently, he never marries and ends his days as an old bachelor.
There may be an autobiographical element to the story, given that Andersen, who was 56 years old when "The Butterfly' was first published, never married. The butterfly's change in behavior from courting flowers to courting a mint plant in his old age could be interpreted as a shift from pursuing heterosexual relationships to pursuing homosexual ones. However, the mint plant is described as being female and she rejects the butterfly.
In early spring, a butterfly decides that he wants to marry a flower. He does not know, however, which flower he should choose as his bride. Knowing that people use daisies to tell their fortunes, pulling off the petals while saying, "He loves me. He loves me not", the butterfly concludes that daisies must be able to see into the future. In order to save time wooing several different flowers, the butterfly asks a daisy which flower is destined to be his bride. He asks three times but the daisy does not answer him.
Having received no help from the daisy, the butterfly decides to start courting the flowers. He decides that none of the flowers he can see would make suitable wives because they are too formal, too sour, too sentimental, too small, too similar to other flowers or simply not attractive enough for him. He considers marrying the apple blossom but decides against it. He fears that the marriage could be a very short one because the blossom could easily be carried away by the wind. He likes the pea blossom very much, until he sees her sister, a withered old pea pod.
The butterfly has still not chosen a wife by the time that autumn comes. By that time, most of the flowers have lost their fragrance. The butterfly then notices the mint plant. Although it has no flowers, the mint plant smells pleasant all over. The butterfly asks the mint plant to marry him. The mint plant replies that their wedding would look ridiculous because both she and the butterfly are now too old to get married. She agrees to be friends with the butterfly but nothing more. After this rejection, the butterfly does not ask any other plants to marry him.
As the weather gets worse, the butterfly takes refuge inside a room that is heated by a stove. He is happy for a while, until he begins to miss the sunshine and the company of flowers. He flies towards a windowpane. It is then that he is noticed by the people of the house. He is stuck on a pin and put in a box. He has some potted plants for company but he does not trust them because he thinks they are too friendly towards humans. He consoles himself by thinking that he is in a position similar to being tied down, and therefore similar to being married.