Legal Question in Employment Law in Massachusetts

You're a little light on the facts here, but if your assistant is over the age of majority, and your student athletes are below the age of consent you could be talking about a crime. If by relations you mean "sex between an older person in a position of authority, and a student," then the police may need to get involved.

If the assistant is an adult, and the student athletes are minors, if I were in your position, I would consult with a criminal attorney about this issue, just to be certain there was no ancillary liability.

If, however, you are talking about a student assistant coach, then the issue is very different; if the assistant coach is a student, then I am not sure what basis you would have to prevent contact between any two students.

If, on the other hand, the assistant is an adult, and your student athletes are, say, college students, then I would discuss the matter with the head of your school athletic department.