My BIL had surgery yesterday. He's in a poly relationship, and his wife and girlfriend went with him to the hospital. They told me the nurse was really nice until both women kissed my BIL, at which point she asked who his wife was and berated their girlfriend. She also said there was a one person rule as to who could be with him while setting up his IVs and whatnot, so their girlfriend had to wait.
But, soon after I got to the hospital, I asked apparently the same nurse where my BIL or his family was and she took me to him despite his wife being there too. She had no problem with me being there while they were setting up.