I just found a way to make people who are more than 'facebook friends' to appear more significantly on your profile.
It's a relatively new feature that I wasn't aware of, called "Featured Relationships"
Hit Edit my profile, then Relationships.
Create a new list, I called mine Anchors (Thanks cunningminx! http://polyweekly.com/2010/11/poly-weekly-260-replacing-primary-and-secondary/ ), and added my partners to that list, and made sure that list appears first on my profile, followed by family, then friends
It's not the same as being "in a relationship with" someone on facebook, but I thought it was a nice thing to do.