I am not sure about the exact manga you are referring to, but it is possible that you are talking about "Komi Can't Communicate" by Tomohito Oda. This manga was quite popular in 2017 and features a character named Komi Shouko who wears a hair ribbon that resembles bunny ears. There may be a scene in the manga where she is crying in the bathroom, but I cannot say for certain without more information.
