You know each other’s weird sides
When you date a person you do not know very well, both of you pretend and try to be better than they really are. A good thing about dating your best friend is that you can hardly scare them off since you know everything about each other, including your weird sides. You are aware of your friend’s strange habits and likes. You do not need to pretend and lie to each other. You can calm down since there won’t be unpleasant surprises.