I also struggle with knowing if my T cares or not. I actually thought about asking him in my last session but didn't. I had already just told him that I am attached and didn't want to go further at risk of sounding completely crazy. While my therapist said he doesn't plan on terminating me as a client, I didn't feel any better after our conversation. I wonder if knowing if he does really care would make a difference in how I'm feeling or not.
I don't think he would answer me straight, I think he would say what your T said; "Why does it matter?" I don't have any good answers for you, but just know I feel the same way!