We’re not friends

So this is kinda weird, my boyfriend has always said that we are not friends. We spend all of our time together, live together, share common interests, talk at lengths every day, but we are not friends. Let me explain- He claims we can never be friends because what we have is so far past friendship. We are two people sharing one life together. He could never imagine sharing his life with a “friend” like that and thinks the term doesn’t apply. He also said if our relationship ever ended, even amicably, he doubts he would be able to have a friendship with me. He thinks it would be to hard knowing what we had together to sustain something he considers to be less. I understand his point of view, but I hear people all the time saying how they “married their best friend”. So I thought I’d put it out to you fine people, can your lover also be your friend or is your relationship something that surpasses friendship?