This is precisely what happened that led to my divorce. My ex deliberately withheld things about himself as much as he actually flat out lied to me about who and how he was. He has a history of addiction and trauma that I knew a little bit about but the full scope of it he purposefully kept to himself. When he ended up attempting therapy, he would quit just as soon as he started and was making progress because returning to a place of denying himself was far more comfortable for him.