Board Thread:General Discussion/@comment-4010415-20141223120240/@comment-26019879-20150125005744

Most likely she spent the majority of her time around the WF, so she most likely only wore the bow when she was going on missions with Adam to try and better conceal the fact they're Faunus. She most likely started wearing the bow full time after she broke away from them. And once RWY found out she was a Faunus, it's entirely possible she stopped wearing it at times when she was in their dorm room.