Life Partner

More PoliticallyCorrect term than SignificantOther (which could apply to a trained assistant dog).

I'm not so sure that LifePartner isn't just as descriptive of a dog

Not to mention that SignificantOther applies to non-permanent relationships, too.

More politically correct, and even more limply milquetoast.

When I hear the term "Life Partner", it always brings to mind this joke: We're partners for life. Instead of a divorce, I'm just going to kill you