Hi..I Have A Friend Who Is In His 50s And

hi..I have a friend who is in his 50s and have been very regular to the gym. he always goes into his "cave" whenever anything goes wrong in his life such as hurt by family members or friend. He starts to drink and is moody and shouts at me when I try to put some positive suggestions. It usually last for three t four days. I am so tired and upset with him as I am always his punching bag. He who is such a nice loving person, changes to be monster at such time. How can I help him. ..