In therapy, boundaries are not merely about the consent of the client. You meet another adult at a cafe/in a bar/wherever and head home with them and you both consent to whatever happens next = cool/fine. In therapy (as between professor and student), it isn't that simple. Therapy in your home, on a Sunday, with someone whose grades you are responsible for is unequivocally uncool, unethical as I see it.

I bring this up in response to your thread about your feelings of jealousy because your feelings of jealousy are just one of myriad reasons why this is not okay.

A prof conducting therapy with a student is not so different from a prof sleeping with a student. (It's arguably worse.) I have been in a university class where my prof was in fact sleeping with one of the students. It set up a dynamic that was unfair and disrespectful to the rest of the class. I had a huge crush on the prof and was extremely jealous too! But although my jealousy may have stemmed from an unmet need to be loved and appreciated etc it was more about the fact that someone else was receiving huge attention and preferential treatment from someone I admired and looked up to.

The fact that your prof/T has years of experience in no way assures me that she knows what's best. In fact I bet if you look at ethics guidelines for your profession it will be stated clearly that a therapist should not have another relationship with the client outside of the therapeutic one.