One time my mom was trying to introduce me to someone, but she was also I guess having an internal meltdown about remembering not to say "this is my son___" so she said, 'this is my sister" by accident. And her face was like "oh no", and I feel compelled to solve all my parents mistakes for them no matter how small so I was like, "Because she's obviously too youthful to be my mother."

So my answer is I'm going to introduce every single person no matter who they are to me as "my sister."

And in a way, aren't we all sisters after all

The is my husband, G. Or Le/Te presento a mi esposo, G. I prefer to always add his relationship to me as well as his name. I guess it’s just the way I was taught to do it by my parents in español so I just transferred that same custom when I am speaking in English.

I dunno

This is Nancy.

I just introduce us both as Mr. & Mrs. Dingus.

I'd probably do it like you do, just the name.

I don't know, I don't remember ever having to introduce a girlfriend. I guess because I'm not very social (including not often having a girlfriend). If I did, I think I would just introduce the by name.

This is Jonny