Maybe this seems like too simple an answer, but does he journal? Maybe you could give him specific issues to journal about like his favorite places to eat and those he dislikes. Or have him make a list of things he does not enjoy doing at certain times and why. Maybe have him make a reward list of places he wants to go or movies he wants to see etc. If it is too hard to him to articulate these things for fear that he would be putting his needs ahead of yours, having him make lists as an assignment may help. Then when he completes a task you can reward him with dinner at his favorite place or surprising him with a movie he wants to see. Rather than feel lied too and having it become the elephant in the room so to speak you can take full control by incorporating it into your dynamic.
Good luck!