While Dean is accepting the fact that he's the loose thread in the family. He's also learning how to cope with his insomnia, mood swings and growing panic attacks all by himself. He wouldn't dare tell anyone what the aftermath is when the bottles are empty, in fear that they'll just think of him even more of a burden. Dean is supposed to be the strong one, right?
12x02 Mamma Mia. This kills me. While Mary thinks that John was a great father, Dean knows that's not necessarily true. He was a good drill sergent, but father, not so much. John loved his sons, there is no question there, but when it came to being a father, he wasn't there for them the way he should have been and Mary really has no idea what those boys have been through with John. Its shaped their entire lives.