It means that the love he gave to the love of his life was unconditional. He gave his whole heart to her. He got hurt very badly by this person and that is why he is saying it. He is scared to give his heart away like he did with this person, scared of getting hurt again. Maybe he still loves this woman very deeply but the hurt is still to close to his heart to be able to forgive this woman. I always say that never is a very long time and also realized in my life that you must never use the word never because you never know when you will have to swallow those words. She must give him time to heal and if he don't mind her closeness then she must just be there for him, support him and try to be the lesser one even if she don't always agree with him and in time he will realize that she loves him very much and that he is also still very much in love with her and that is why he can't move on with someone else. I hope that I was of some hope to you my Dear
