It's the same thing with my babysitter.
She lives with her two sons, her sister, and then another woman. They seem to do everything together as a couple (like they went OOT this past weekend to concert...Just the two of them). The house is in both their names (yes, I looked up the owners on record on the county website...I'm nosy). DH said that our sitter said to R (her housemate), "Oh I'll have to get you on the list so you get the emails for the boys football team so you know what's going on." So obviously, R is just as in charge of the boys and their schedule as my sitter is.
It doesn't matter either way because I love, love, love my babysitter and she adores DefConn. And I like her 'partner' a lot.
I just wonder 'are they or aren't they?' because she didn't introduce R as her partner...She just said, "This is R and she lives here," when I met R.
DH and I have talked about it a couple times because we both wonder.