If the oppurtunity arose, I’d use ‘partner’. This has no specific association with same-sex or ‘alternative’ couples to me.
‘Mate’ to me refers specifically to the biological act of sex and procreation, as in the verb ‘mating’ and phrases like ‘the bird brings twigs for its mate’s nest’. The Brit use of ‘mate’ to mean ‘friend’, ‘buddy’ is one of the most confusing usages to me; I jusr can’t seem to become accustomed to it. Except in Monty Python skits.
F***puppet. In polite company, it’s “this guy I’m maybe sorta hanging out with”. Anything more committal and I start hyperventilating…
I’m with Sunspace, “mate” sounds too Wild Kingdom for me. I’m not all that keen on “partner” either. I usually use “boyfriend” or “significant other.”
Boyfriend. Fiance and then husband if we ever get that far. SO is a little odd in conversation; I associate “partner” with committed homosexual relationships, and “mate” is just plain odd.
I, too, associate “partner” with committed homosexual relationships, so I just say “boyfriend” (when I have one). I agree with Sunspace and MaddyStrut about “mate,” though I have no problem with the Brit usage. I think I’ve only used the term “partner” once, and it was to refer to my then-bandmate (a kind of business partnership).
Unless you know a gay person in a committed relationship who is also in business with someone, I’d think that you’d be able to tell from the conversation’s context which definition of “partner” is being used. I also seem to think that I hear “business partner” quite frequently (maybe due to others sharing your observance), with “life partner” sometimes but not nearly as frequently.
(And if you do know a gay person in a committed relationship who is also in business with someone, tell him/her to be more clear! ;))