adhd boyfriend shut downs - advice please

hi guys. question from me about my boyfriend with adhd. together since january.
we had a fight at the beach because he wondered off to get chips as the fireworks were about to start, which i drove us an hour to watch together. i watched the whole thing alone and i know he didn’t mean it, but it really upset me. i had a cry, he came back with the chips and got super defensive. said some harsh things. made me cry more. he knows all i need is some comfort in moments like that. we are both in therapy for our own issues and he used to be SO defensive, and he’s really grown. i’m so proud of him but last night it’s like he used to be. it sucks.
after getting defensive he said sorry a lot in the car after i explained how alone it makes me feel, and how i feel like i can’t have feelings but he can. the sorry didn’t really cut it at the time, i needed to calm down, i was so upset. although he did say sorry and said ‘im emotionally unavailable right now’ and then came the shut down.
he hasn’t shut down on me for a long time, and not because of something he’s done to me anyway. he clearly entered a shame spiral which he hasn’t done for a while, probably because he saw he really upset me and how badly he handled it.
when we got home he left, said he was sorry, i haven’t done anything wrong, it’s all just noise in his head, he can’t be what i need right now and dipped. he came back 10 minutes later, came in, sat down in silence, left again and said it’s pointless he’s an idiot for coming back. i guess that was him trying to repair things but being unable to at that time.
i hate when this happens and i know he doesn’t mean it, i can’t imagine what happens in his head when he’s in a spiral like this. i don’t know what its like so i try my best to be patient.
please can i have some advice on what to do in this situation? i haven’t spoken to him since last night, i don’t know whether to leave him alone, reach out, what do i even say? could i have done anything better?