With friendships, after a while you just don't care. You feel comfortable enough with the person. You don't constantly exchange, you don't constantly prove yourself worthy of them, you don't constantly care about their every action around you. You owe them nothing but good times, they owe you nothing but good times.
It is much easier to talk about personal problems with friends than with your partner. You don't have to hide anything for fear of being left because of your problems. It's really nice not having to constantly analyze everything you say just in case.
Because there are no expectations in a friendship, there is no shame in not talking for a week or two and picking it up again later. In fact, you can be yourself with your friends and not be who your partner wants you to be. I find that friendships are a much more intimate connection than any romantic or sexual relationship has given me. I feel supported and loved for who I am by my friends.
Read more: Friendship is much better than relationship