[gymnAnemoe]

It sounds harsh, but these things can cause problems. Speaking from personal experience (don't ask), a little gentle intervention will probably help ease the tension a bit. The last thing you want is things getting out of hand - in a close-knit dojo environment it could cause problems for more than just the two at the centre of this.

If you don't mind me asking, how old are the people involved?

Edit: Actually, reading nodachi's post - is it interfering with anyone's training? If not then it probably doesn't need as direct action as I suggested.