Technically no, but to be honest I doubt anybody would even notice in a big accommodation setting that you had somebody else in your room all the time. You'd just have to always be there to let them in and out. Unless somebody else reports you for it. I know people who had boyfriends/girlfriends 'staying over' for months at a time.
But some Universities have special accommodation etc. for families and couples. Fairly sure I've read about that in a few places. Might be worth asking about?