I'm a teacher and I was once on a similar situation:
I used to be quite close to my students, they would ask me and consult to me about their daily lives and whatnot. However, because I didn't set the correct boundaries at the time, they started to engage me as their friend, not their teacher, and a couple of girls became quite entitled about the time I gave them, which in turn gave fuel for other students to start spreading disgusting rumors about me. You can imagine the kind.
I had to stand in front of my class and quite seriously remind everybody that:
a) I was their teacher, not one of their classmates
b) The time I gave to my students was as a teacher, nothing more
c) Spreading rumors about people without properly talking with them is a terribly selfish and damaging thing to do.
Afterwards, I stopped consultations and put a barrier with that years' students. Teenagers are complicated and, as adults, we sometimes have to put on a more stern attitude to avoid missunderstandings. It sucks and all, but in today's world we have t be strategic about every interaction, all the time, to cover ourselves.