in 3.10 the scene with dean and dream!dean is soooo...like he’s now critical of john, dream!dean says that john demanded so much from dean but he “doted on sam” and loved him. i don’t know that sam would describe his childhood as doting or that that’s supported in the show but like…that dean thinks that makes so much sense. he views john’s control over sam as overbearing but loving protection for sam’s good, which informs how he shows love to sam - by doing the same thing.
whereas sam views being left alone for long periods, controlled, and monitored as him being treated as an outsider in the family unit. and he says they fought all the time! and compares john to other dads they meet who are controlling, angry, etc. but dean can’t see what sam experienced from john as abusive/bad because then it calls into question everything he’s spent (and continues to spend) his life doing to ‘protect’ sam. he needs to view it as a form of love.