Word Confusion

I met a friend at the IMA last night to view the new Egyptian exhibit. She brought along another friend of whom I had not previously met. While we were walking around the museum the friend asks me if I want to got a Spa Party at her "partners" house. I said sure that would be fun, since the visit to the museum would take no longer than 1.5 hours. When she said partner I had assumed she was gay. However, later in the conversation she referred to her partner again but as a male. I got very confused. I had only heard people use the term partner in reference to being in a gay relationship. Since I didn't know her well I didn't want to question her to get all of the details. About an hour later we arrived at this persons 1920's downtown apartment and I was introduced to her partner who was a man and then to the other man who was actually giving the spa party. I became more confused as it was apparent that these were two gay men who lived together and were in a relationship. I preceded to enjoy the pampering of the spa party, I tried some nice face wash and some foot scrub in their bathroom. We then went to the living room for a sampling of the green face mask and various other products. Throughout the evening she kept referring to this man as her partner and I became even more confused. About the time I was ready to leave which was four hours after I met her, a light bulb went on over my head. All of these people at the party worked in the health care industry and most of them were EMT's on ambulances. They were "Partners" on the ambulance...AKA co-workers. I just didn't understand their industry jargon. I am glad that I didn't have to live in such a state of confusion any longer.