More about teacher and student relationships
Most of the rules I have for groups or teaching, I established because I learned the hard way that I can't just expect people to act right.  It's unfortunately true that people still won't act right even when you spell it out, but at least they can't say you didn't warn them.

For example, I have a hard rule about dragging other people en masse into personal disputes.  I don't mean asking individual others who know me or who are in the same group for their opinion about a situation, or possibly asking someone to mediate; that's usually a good idea.  I also don't mean conducting a group conversation about a group concern.  But mass e-mails or having a group conversation about an individual who is not present, for anything short of sexual misconduct or theft, is an absolute deal-breaker. I tend to object strenuously when I'm just a bystander. If I'm the topic of conversation I will be outraged and my trust will be nearly impossible to earn back.  I think it's true for most people that if you're going to call a meeting about them, virtual or in person, it better be either you planning an intervention or something so bad that your relationship with that person is an acceptable casualty.   You'd think that would be obvious...I would have thought so...but evidently not.

It goes both ways, of course.  I do not discuss disagreements with individual students or why I ended my relationship with them in public or semi-public; I normally don't discuss it at all unless asked.  That's tricky in a situation where they were part of a group; there's both a sense of owing other people an explanation to some extent, and of not wanting to poison or disrupt their personal relationship with people who have been their friends.  I have heard second-hand stories of teachers who frequently blackball students, forbid their current students to talk to that person, and badmouth them to all of their former friends.  I never wanted to do that.  

That is partially because I do not think that someone being a bad fit as a student for me means they are a bad fit for my tradition, and I am conscious of the possibility of damaging someone's reputation among my peers.  I'm not petty enough to do that just because someone pissed me off.  If I think they are morally questionable enough that I should say something about it, of course, that's a different matter...but as I alluded to above, there's not a lot that rises to that level.  

The fundamental reason though why I don't do that, and why I will be unamused to the point of a permanent break by anyone who does it to me,  is because it's plain old shit-stirring.  Any behavior that seeks to escalate a conflict, rather than diffuse or resolve it, in a situation which does not have overriding moral concerns that rise to the level of potential damage to the community if left unspoken, is drama.  By definition.  And if you bring the drama, then I will be strongly motivated to eject you from my life and make sure you never come back.  

Pro tip:  So will most of the other people involved.  Except the ones who love drama.  And those people are not your friends. 

I've learned that keeping my mouth shut has a price.  Generally, that other people are eager to fill the vacuum with their version of events.  That can be very hard to take, especially when I can provide proof that they aren't telling the truth, but that could still just be feeding the drama.  I've let myself be talked or talked myself into saying more than my original instinct said I should at times, and nearly every time I have regretted it.  I'm prideful and prone to ride out with a sword for Truth, and I'm as tempted by gossip as the next human being, but I've come to the conclusion that being as meticulous as I can about interpersonal conflicts (which I hasten to say may not look like another person's idea of meticulous, but that's another topic) is the way to go, even when it stinks.

From a purely witchy point of view, any kind of drama is leaking power at best.  It feeds the ego but at the expense of alignment and being centered in your own power.  At worst, stirring up bad feelings and upsetting people for its own sake is also apt to attract astral "critters" and the kind of hungry spirit that likes to feed off those kinds of emotions...and once you've got some of those around, you may find yourself in more and more conflict-filled situations that don't go anywhere, as those critters use you to generate their next tasty meal.  Most people know individual Pagans or covens who fit that description, and I suspect that for a lot of them that's why.

I wish to make it clear that I don't classify all conflict as "drama," and the Gods know that I am not afraid of getting all up in someone's face when I think it's necessary.  But well, if I have a problem with you, you'll know it because I will tell you.  Privately and directly first, and I will attempt to resolve whatever it is that way before I do anything else.  Should I determine that isn't working,  and I don't think I can just drop it, whatever I do next will be out in the open where you can see it.