Funnily enough, while I think I wouldn't feel okay about referring to "my wife (or similar)", I have collaborated with my sister and we've co-presented at a conference once, and it was sort of fun that it was a family venture. Also, in NZ education circles (it's a small community) there are two brothers, both educational historians, and people do refer to them in the field as the O brothers.

Maybe it feels less of a big deal to refer to the relationship when it's not a relationship that's about fucking.