Romanticism is a style of literature and visual art that was pioneered and became popular during the late eighteenth century and early- to mid-nineteenth century. However, the term "Romantic" can simply mean having Romantic elements, and not necessarily elements specifically from the Romantic Period movement. It is worth noting that William Wordsworth is one of the central figures of the Romantic era, especially in his native England. Wordsworth helped develop English Romantic poetry during the era, along with fellow English Romantic poets John Keats and Percy Bysshe Shelley.
With that context, Wordsworth's poem, "We Are Seven," has Romantic elements. For instance, there is a conflict between two of the main characters in the poem. The narrator and the girl have a confrontation. In Romantic literature, relations between characters are often explored, especially tensions and complex dynamics.
Another Romantic element in the poem is the subject of death. Many of the English, American and continental European poets during the Romantic era were obsessed with death, and examined the concept of death from various perspectives. Death and religious elements, namely Christian, are also closely related within the Romantic style, and this relationship can be seen in Wordsworth's poem.