You have common interests
Best friends are people who have a lot of various things in common. They like the same kind of food. They are keen on the same genre of movies and listen to the same music. Common hobbies make people close friends because they have a lot of exciting topics to talk about. Travelling with your best friend is another advantage and if you are in a romantic relationship with your best friend, then you know that staying in the same room with the person won’t cause any issues and misunderstanding. Sightseeing tours, concerts, excursion and eating out do not annoy you.

You know what irritates and annoys your partner
New people seem to be nice and gentle. You meet someone new and think that that’s their true nature. Their manners are usually good, they are polite and have no habits. But the truth is that there are no perfect and impeccable people. After a couple of weeks or even sooner you realize that the person was pretending. He or she may have habits that are inacceptable and disgusting. Your best friend is a different story – you know everything.