A dramatic situation is defined as one in which the characters of a story are in engaged in conflicts of one sort or another and these characters and conflicts interest and compel the reader's attention. Carlo Gozzi and, later, Georges Polti identified 36 types of literary conflicts. Some of the classic types of conflicts are:
Human against Human
Human against Nature
Human against Self (inner conflicts)
Human against Supernatural
Human against Society
Human against Fate (or Destiny)
Human against Machine
So, a dramatic situation embroils one or more sympathetic (i.e., readily sympathized with) characters into one or more conflicts against themselves or against external forces.
Shakespeare's Sonnet 18 is a quiet contemplative sonnet in which the poetic speaker explains why his beloved is more wonderful than "a summer's day" and therefore worthy of immortality granted through being the subject of an eternal sonnet. Thus the dramatic situation must, of necessity, be a subtle one.
The characters are the poetic speaker and the implied subject of the sonnet, his beloved. The setting is nature with elements of "rough wind" and "darling buds of May" and the Sun, the "too hot eye of heaven," and "nature's changing course." The primary conflict is a surprising one and only indirectly related to the beloved and sonneteer. The conflict is that of Nature against Nature as the rough winds and burning sun chases "every fair from fair" and into declining beauty as the buds are shaken and summer's green growth ends while "nature's course" changes from full bloom to fallen blossoms and withered leaves.
The dramatic situation therefore is that (1) the sonneteer has removed his beloved from that conflict; they look at it as if it were through a window glass: the conflict does not touch the beloved. Furthermore, (2) the sonneteer insures that the conflict of Nature (physical nature) against Nature (natural human beauty) will never touch his beloved. He insures this because he will bestow eternal life and immortal beauty upon his beloved through the words and lines of his sonnet: Sonnet 18, the sonnet that immortalizes against Nature's decline.