But did he love just enjoying the balcony? Maybe that's exactly what he wants in a vacation? If you decide to go concierge, do at least a one bedroom, so you can have your dinners and even Palo in your room. You will get to enjoy the ship and he'll get to relax. I don't imagine the concierge hosts will bother him if you ask for minimal contact.
My DH isn't an introvert, but he doesn't like crowds. He'll happily go to the shows and do the movies and MDRs, but he refuses to even come up for the fireworks. He has no interest in the parties or meet and greets or even just sitting up on deck. He loves the verandah and will sit out there fish watching (he actually saw one once). It makes him happy. I, however, flit around the ship so much that if it were just me, I wouldn't even need the verandah (although it is nice). Everyone cruises differently.
That said, if your DH feels pressure to share time with you or if you feel lonely if he's not with you, then this might not be for you both. You have to be able to happily experience things on your own and not feel bad about the other person's choices.