Question about table B09008: Presence of Unmarried Partner by Household Type for Population Under 18 Years in Households

I'm trying to wrap my head around the cases that would be in lines 6 and 12 of Table B09008 (children in nonfamily households).  At first I thought this was possibly 16- or 17-year-olds living with their boyfriend/girlfriend/spouse, but then the universe says that it excludes householders, spouses, and unmarried partners.  So then are these teenagers living with roommates/nonrelatives?  That explains line 12, but I can't think of a case that would be captured by line 6: children in nonfamily households, unmarried partner of householder present.  Can anyone point me to an example of a living arrangement that would fall into line 6 of this table?  Is my understanding of line 12 correct?  Thanks!