Yeah, I would say so. It takes someone who is hopefully one of your best friends, and moves them to a permanent (or in my ideal mind permanent) status where their relationship to you is no longer mutable ("if she pisses me off enough I can just fucking leave" or "I can't deal with this any more and I need a break from being this person's friend") to now - first having an understanding that the people you love and are around all the time are going to piss you off, and while it's unfortunate it's actually kind of okay and natural from time to time - and then, trying to move past those altercations with love and acceptance, or at least patience (and apologies as warranted). There's an element to it of really truly knowing a person too, or when you're in a family of knowing the general behaviors of each member of the group - and I guess of just general acceptance of these people's behaviors (as long as they're not self-destructive, etc). I think it's the acceptance angle that's a big part of it.

I think the other part of it is kind of a rubber-band like willingness/commitment to pitch in. For instance I moved back with my parents at the start of the month. On average, I come home and do three chores a day. I don't do them because they ask me to. I don't keep track of how many chores I do or dishes I've loaded. In a roommate situation even if I was living with my best friends I wouldn't be happy if I were doing the majority of the chores for the household, because it's not fair and those aren't my dishes and yadda yadda yadda. I feel like with family, you try not to tally up "good marks" and "bad marks" and keep things even. You just pitch in when you can as much as you can, and trust that the rubber band will come back for you when you need it. I'll be traveling to VA soon and I know without asking my parents will take care of my cat. That's some of my payback.

I would expect/want that from a spouse, but would never expect it from a roommate. Sure, I'd ask, but if my best friend/roommate has plans for that weekend I'd find other arrangements. With a spouse or with family I feel like there's just this extra layer, an element that you trust that they will make something work to help you when you need it.

If I were in jail and married, I'd call my spouse, then my family, then my friends for bail. (Hopefully it's not that expensive and they don't mind helping me out!) If I were in jail and had a significant other, even if it were long term, I'd call my parents/family, then the s/o, then my friends. (I'd also ask my family to contact my s/o if I really did only get one call, or vice versa with the marriage situation.)

I think it is a subtle shift and I think this is probably a pretty personal distinction but that is kind of where I would draw it.

EDIT: I admit I started making a false dichotomy between best friends/family here, when clearly "significant other" is a middle ground, but I think that's partially because of the tier structure, and they're the closest things to compare to.