Hi, Sounds as if he has a big shield up, which usually means he has been hurt or betrayed in the past. This macho image comes from fear. Fear of intimate relationships, of letting anyone get too close, fear he is not as good as other people, etc. Fear will stagnate growth. Facing the fear of allowing others to see the vulnerability is the way to get healthier. This is probably not something he can do simply by reading. Having the knowledge to flip the light switch doesn't turn the light on unless it is followed by action. Action is required on his part. Having the courage to do this is s bit more difficult.
The fact that he is aware of his behaviors is a plus, because hopefully he recognizes how destructive this is to his relationships. And this could be the motivating factor. He is probably quite sad on the inside despite his macho image.
There are many books from John Bradshaw that will describe these types of characteristics, and he can educate himself. However, a good therapist will help much more. Finding one that will not "sugar coat" the truth from him will be vital. Seek someone who specializes in family of origin issues, and they can assist in "unpeeling the onion," so to speak.
I am glad you are assisting him. I hope he see how much you care about him to help him. Please let me know if you have further questions.