Yes, but have you ever tried living with your best friend for a long time (at least a few years)? I promise you that the dynamics of ordering the wrong sandwich will pan out very differently. While being “friends” is paramount in any relationship by itself it is not sustainable.
I’m sure you’ve heard stories of roommates, who were great friends, yet had these friendships ruined because of money concerns, cleanliness, who is doing the dishes tonight, etc.
You need multiple pillars to hold up a long term relationship. Friendship is one of them, but so is trust, honesty, love and passion. If any of these become damaged and not addressed in time, the relationship will inevitably fall apart.