I've been thinking up a list of reasons why heterosexuals would refer to their significant others as "partner." Here is what I came up with:
- When the couple considers themselves at the status of married, only without the license.
- When the one views the other as an object, less than human.
- "Partners in Crime." You know, when they've been struggling through their differences for the whole movie, then the dominant one reaches out a hand and offers equality by calling the other "partner..."
- Cowboy friends. It's not a gay thing, it's a cowboy thing. Although arguably... well, let's not get into that.