What is the proper term - gay, homosexual, or same sex couple? I keep going back and forth.
All are fine.
Not sure, my homosexual friends don't seem to care. But I use homosexual as gay is often used as a derogatory term. Ie "that is SO gay". I never say that so want to be accurate when I speak.
That just means you shouldn't use gay in a non-gay, negative context. But you can call gay people gay! I don't generally use "homosexual" when I'm talking about people because it makes it seem like it's about sex and only sex, which it isn't. But that's just my preference. It's why people stopped using "lovers" to mean gay partners, because it makes it all about sex. My dad's husband is his husband, before that he was a boyfriend or a partner, but partner can sound like business, so it's sometimes confusing.
I don't use the term partner for hetro or homo relationships. Oh and I know what it means I usually do not describe people using their sexual preference anyway, unless talking about the topic itself, not in an explainary way to describe someone.. IE I don't use it like, man/woman.. or brown eyes, blue hair.. skin color or height. I only use it when discussing sexual choices ;).
I use gay and my gay friends are not bothered by that.
Partner does sound businesslike. A guy I work with has a partner and it always makes think work.
I have a business partner in my side project and we stopped saying just "partner" because people thought it meant we were in a relationship instead of working on a project! Funny.