Trademark vs. Copyright.

She was upset. Very Upset. I could hear it in her voice which cracked with emotion. “You can’t do this!” she said trying to control her feelings, “You can’t use that title. It’s my title. I have used it for years in my writing workshop and I almost have a book published with the same title.”
Now almost have a book published is a red flag area for me anyway. I think everyone on the planet has a book that is almost published. “I’m sorry ma’am,” I say in my controlled but sympathetic tone, “The title you want to use is not the main title but a subtitle for the book”
( I have a copyright on the Title! )