If he breaks up with you and you can't eat, sleep, or think without him than that's not healthy. You don't love yourself enough to know that it was just meant to be and there's nothing you can do to change his mind. Breakups are the most painful because that person is choosing to not be with us anymore. We end up thinking, "what is wrong with me?" "Why won't anyone stay with me?" We gave so much of ourselves that there's nothing left for us. Once we're out of those relationships, we're left with ourselves. We need to learn how to nurture ourselves and understand that that wasn't only relationship left in the world. To have healthy love we learn that we have to love ourselves in order to have healthy love with someone else.
That time alone is perfect for you to focus on what you need to change in a relationship because we have flaws and things we need to change. You can read self help books. They help you see what you need to do more or less. I read a lot books and learned. You can't change overnight but at least you recognize your faults and you learn what you need to change. It helped me a lot see the things I was doing wrong. Even though you kind of know, it still helps you and you will notice things and grow from it. You deserve to receive as much as you give. Don't loose yourself in a relationship and only focus on giving him love and attention. You have to love yourself and learn how to nurture yourself.