Maybe we need to clarify how we are defining sex. When the OP says
Is she using the Bill Clinton definition of sex? “I did not have sexual relations with that woman, Miss Lewinsky.”
@kenken5145 I don’t think you realized that people in the throws of new physical relationships are often unaware of how their public display of affection may make others feel uncomfortable. Or how inconvenient and uncomfortable it is waiting for your roommate and her boyfriend to put their clothes back on just so you can open the door to your dorm.
I liked the suggestion up thread about each roommate having the room to themselves and their invited guests one Saturday a month, that seems very fair or just make a flat rule about no visitors in the room.