Let it be noted that all of you were given dormitories for a reason. They are for your own privacy - a member of the staff will only intrude upon them in a dire emergency.
The library, the classrooms, the great hall, and the entire rest of the school, however, are not private places. Public displays of affection are acceptable. Anything more inappropriate for a school setting will be dealt with seriously and immediately.
I do hope I've made myself clear.
To other staff members - I would encourage more rigorous patrols of the hallways and classrooms when any of you have a bit of free time.