Is he eating, pooping and peeing like normal? If he is, that more or less rules out sickness.
It sounds to me like he’s getting into puberty for real. It can be rather like flipping a switch and we hear about it a lot on these Forums: Sweet cuddly baby bunny suddenly doesn’t want to be lifted, held or even pet and seems scared of people or shows aggression. It’s a phase that young animals go through, and it will subside as he matures, but adult bunnies most often don’t like to be lifted or held. If you are planning on having him neutered, you can start thinking about that now.
The super-good relationship you and he has developed is not down the drain. It’s still there, all of it. This is just hormones and the process of growing up. If you have him neutered, this phase will be done with sooner than if you keep him intact, but intact animals do progress out of this phase too, it just takes them longer.
So be patient and kind, don’t force yourself on him, pet him mostly on the head, reward him when he approaches you – he’s like a teenage kid now more or less, which in many cases means confused and overwhelmed.