I think you're thinking of a line from when he's trying to interrogate Rey with the force. Something close to "Han Solo... you think of him as the father you never had. He'd have been a disappointment."
Yes that is the one. So how did he disappoint? If you had a dad like Han Solo with a friend like Chewie hanging around. How is that bad? He must have really changed into a different character between Ep6 and Ep7.
EPIV: A smuggler with a concience, in the moment where it counts he is selfless and returns to help the rebels land the killing blow on the Death star.
EPV: Being a general for the Rebellion, helping the princess to escape, sealing their love.
EPVI: Getting rescued by his love, being a general in the Rebellion again, leading the assault on the shield generator on Endor.
EPVII: Back to being a smuggler, abandoned his son, his wife and the Rebellion, then in the last act he is leading the assault on the shield generator on Endor again.
How comes? I really, really hope they have some meat to fill these blanks in EPVIII. It just feels like a convenient retreat for now. Like the hero telling his buddy in the sequel that it "just didn't work out" between his love interest from the first movie and him so they could get a new girl into the sequel or start from scratch again cause it was too boring to find a way to work the actual grown character development into the story.