Any ideas as to why I was abruptly ghosted by a guy who seemed EXTREMELY into me?

I (25F) am genuinely confused by a situation and would love some outside perspective.

A few months ago, a guy (21M) messaged me on Instagram. He lives across the country, but he travels to my city regularly for work. We started talking and quickly became part of each other’s daily routine.

For context, he was the pursuer from the beginning. He would text me every day, call me almost every night, wrote songs about me, talked about future plans, and even offered to fly out and meet me in another city during one of my work trips to take me to dinner. There was never any ambiguity about whether he was interested. If anything, I was the hesitant one because he’s four years younger than me, and I told him multiple times that the age difference concerned me.

Eventually, I relaxed and started enjoying getting to know him. We had a lot of playful banter and would jokingly tease each other about who we were spending time with.

One morning he sent me a normal good morning text. I replied with a good morning text and made a joking comment asking about his whereabouts the night before. It was definitely a cheeky joke but It was completely in line with the kind of banter we’d had for months. No argument, no tension, no awkward conversation beforehand. And then… he never responded.

Not later that day. Not the next day. Not ever.

Four days later, I sent one message saying that if I had somehow offended him, I was sorry, but I was confused by the sudden silence. That message also never got a response.

It’s now been long enough that I’ve accepted I’m not hearing from him again, and I have no intention of reaching out further. I’m not distraught or anything but it’s just definitely a little hurtful. I actually really enjoyed talking to him

What I can’t understand is the abruptness. We’d never met up, never hooked up, never slept together, never had any major disagreement. Literally less than 24 hours earlier he was discussing plans to potentially meet me during an upcoming work trip.
what do you think happened here?