Derealization After Meeting my Partner I Haven’t Seen in Ages?

So we used to know each other in school but got separated but still texting from 2023-now. We hadn't seen each other in person since early 2023 and we'd been hyping up meeting and finally we threw together a quick plan that worked today.

When I saw him it felt like I was imagining the entire thing. He did not have a mind of his own and was the product of mine, similar to a daydream. Throughout the whole meeting it felt absolutely fake and when I put my head on his shoulder it felt like I was doing it in a dream and he was a dream character when he returned it. Then I left and the whole thing still feels like it was a dream (we both have derealization also and he claimed it also felt like a dream for him but I believe it was just my mind making "him" say that).

Why did this happen? I've never felt such intense derealization. No cap it felt exactly like a dream.