It sounds like your baby bunny is growing up. Baby rabbits often accept or even enjoy being picked up and held, adult rabbits as a rule don’t want to be picked up or held. It’s an instinct, not a choice. Being picked up is the first step towards beconming somebody’s dinner, from a bunny’s point of view. It’s not something you’ve done wrong, it’s just a natural part of your boy being a teenager.
Most adult bunnies enjoy being pet on the head, nose, ears and nape of neck. Adult bunnies can very well become very cuddly and fond of pets, but on their own terms.
Adult bunnies also spend most of their day lying about. Rabbit are crepuscular, which means they’re active at twilight. So mornings and evenings are their active periods, during the day they like to lounge.
All in all your boy sounds perfectly normal and you seem like great bunny parents. It is better to have him fixed and fully healed (about 4 weeks) before you introduce a second bun. Intact males fight like mad dogs and intact boy + girl of course will mean babies.