My landlord has access to the apartments and was in my place for some minor repair work recently. Seeing all the girl paraphernalia (make up, lingerie, clothes, etc) he spoke to me about when I got home. He told me there would be an additional charge for a second tenant. I was confused at first,, then the penny dropped and I started to laugh. I explained the situation, and even showed him a couple of pics on my phone.
Other than looking a little disappointed that he couldn't get more rent money, there wasn't a problem. Although I don't that he quite believed me until he ran into me one evening as I was going out.