I had an ex boyfriend like this. Constantly fucking late, never took accountability, acted like it was beyond his control, made ME call/text him to wake up (like yours, he wouldn't even with calls+texts), would get mad at me for getting mad at him... It was a mess. I put up with that shit for years. It kept getting worse as time went on.

Once he was late for our date by over three hours. I left because fuck it, why would i wait, and he leaves the most pathetic and angry voicemail.

Turns out that he had ADHD. I found that odd because he was medicated for it... And then i actually found out - he was staying up late playing video games, which is why he would chronically sleep in until like, 6pm.

It's not your job to parent someone who's supposed to be your equal.