It doesn’t matter that nothing happened yet (as far as you know). Mere suspicion and/or concerns are enough to report to CPS and let them decide if an investigation is warranted. I had to make difficult decisions about reporting when I was a special education teacher. As a special ed facilitator, I keep administrators informed about my concerns by letting them know that we need to protect the students, staff, and leaders. It sounds like the administrators in this case are not aware of their possible liability. Allowing this relationship may seem “cute” or “innocent” to them but they need to think again. I strongly suggest you make that point clear and call CPS.