1. You know all of each other’s quirks.
At the beginning of relationships, most people are nervous about revealing those odd eccentricities they have out of fear that the other person will find them strange. But your best friend already knows that you sing nonsense syllables when you’re nervous, so you can just be yourself from Day One of your relationship.
2. You don’t have to wade through new-relationship-white-lies.
New relationships usually begin with those awkward moments when your date doesn’t realize you hate raw fish with a fiery passion of the fire that your fish should have been cooked on, and takes you to a sushi restaurant, where you then lie and have to order edamame and steamed rice and hope they don’t notice. All for the sake of not hurting their feelings or making them feel awkward. But in this best friend relationship? NONE OF THAT APPLIES. It’s beautiful.
3. You know you’re both in it for the long haul.
Both of you had to think long and hard about whether or not you wanted to risk the great friendship you had for a relationship, so neither of you are particularly fond of the idea of breaking up over tiny annoyances. If there’s a bump in the relationship, you know that both of you are going to give all you’ve got to work though your issues.
4. You already know each other’s relationship pet peeves.
Before dating each other, you complained to each other about the all things your boyfriend/girlfriend did that pissed you off. So now that you’re in a relationship together, they know to always keep the toothpaste capped, and you know not to check your phone when you’re out on a date without ever having to confront one another.
5. You don’t have to worry about relationship histories.
Not only do they know about all of your past relationships, but they’ve witnessed most of them. You don’t need to worry about explaining that, yes, you’ve dated a children’s party magician, but he was a really good kisser, because you hashed that out months ago when you both went to your nephew’s fifth birthday party.
6. You already know your family likes them.
And vice versa. You don’t need to have to dread the moment when you introduce your significant other to your big, loud family, because it’s already happened, and they all approve.
7. The “first fight” isn’t such a big deal.
The two of you have been fighting for ages, so the fact that you’re arguing about that Italian restaurant that you love and they hate means relatively little. You’ve worked things out before, and this time isn’t any different.
8. You’re super comfortable with each other.
You don’t need to obsess about what you’re wearing each time you see them, because they’ve already seen you in a ratty t-shirt and those sweats that you’ve worn for three days straight.
9. They’ve seen you at your worst, and didn’t run away.
Life has its ups and downs, and your best friend has seen you through them all. You don’t have to worry that they’ll be the fair weather significant other.
10. They know how to handle all of your emotions.
Your best friend has seen you angry, sad and everything in between. They know that you should be left alone after arguing with your parents on the phone, and they should bring over Phish Food ice cream when you’re re-watching Grey’s Anatomy.
11. You genuinely like each other.
You don’t have to worry that your relationship is simply physical, and that the love will disappear when your looks do. You know that if the two of you make it to 80, you’ll be perfectly happy sitting on your front porch, playing bridge, soaking in the other person’s company.