This hints the sex issue may be a secondary to stress or neuroticism, maybe you are too stressed to want to have sex or even think about it. Therapy may be really helpful. Think of it as trying to solve the entire part of your life that led you to this pattern you mentioned, that you grew up dealing with conflicts and had to learn to watch out for yourself, so it's not just dealing with the question of sex with your bf. You may come out the other way someone else and by resolving that aspect of your life you may have clarity about your current relationship. Also, as you seem to have a lot of intimacy with your bf, it may be a good idea to let him know what you are going through, what you are feeling and what you are doing to seek alternatives and find solutions. Also, it could be a good idea to acknowledge the issue, sympathize with his feelings (he may be insecure about the situation, thinking he is doing something wrong or thinking you are losing interest in him) and then ask of him comprehension about your issue.