The primary speaker in the poem is the teacher; the audience is the teacher's class and also the reader of the poem.
When a student says that the characters in another student's writing aren't "making love" and are instead "fucking," an older student speaks up. She says that they could be making love and that using the harsher term will take the audience's focus off the rest of the poem. A boy in the class disagrees with her and says that you can call it making love to tell your partner what she wants to hear. Then the writer insists that it was herself in the poem, and it felt like love.
The teacher then identifies themselves as the speaker. They do so by saying, "to me, their teacher." Before this, the reader isn't aware of whether or not the person speaking in the poem is a third party, another student, or someone else. But once you know it's the teacher, you understand that their audience in that moment was the class, and their audience in writing the poem is you, the reader.
In the sense of the story the writer is telling, the rhetorical situation has three parts. The first is the purpose of the scene, which is to show the importance of words and how writers and readers can disagree on terms and meanings. The second is the audience of the scene, which is the students in the classroom. The third is the constraints of the writer and the audience. It's impossible to know how the author felt about the issue in the poem, but the audience members each applied their own filter. The older student and the young woman that wrote the poem understood sex as making love—something two people with feelings for each other do. The older girl, the boy, and the teacher each dislike the term "making love" for a variety of reasons, and those reasons are likely the results of their own experiences and understandings.