Why did he ghost?

I met a guy online from an app right before me and him were leaving for our vacation. We spoke on the phone for an hour and after he said we would meet up when we both return. After that, we spoke for two weeks straight while we were both on vacation. We spoke on the phone, facetimed, and messaged each other. He basically initiated all of this and asked to facetime multiple times and one time we spoke for an hour. During our time talking, he kept telling me I look great, that we get along, and that will go out when we are both home. He never gave me concrete plans though. The day before he was supposedly leaving his trip, he ghosted me. I didn't say anything bad and we didn't have an argument. He just never replied to my last text which I asked what concert he was going to for New Years. I know no one knows for sure what happened, but any guesses? It's just so bizarre... Thank you!

Updates
4 mo
Error: we did not go on vacation together---it was our own separate trips.
Why did he ghost?
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