you can
Include phrases like:
You really helped me understand when I was struggling.
Thank you for tutoring me in algebra this year.
Your class taught me how to be a better student.
Thank you for your patience.
You helped me see what I could be.
You are the best teacher ever!
I will never forget you.
<span>B. putting a comma in between the complete sentences.
Simply putting a comma between the complete sentence phrases will not keep it from being a run-on sentence</span>
It is a poem at the least. If you require more I assume it is fiction, as most poems are.