In the original, Slow and the anime fan were fused from the moment he reincarnated. He's both people at once. Here, in the midst of the battle with the dragon, we get a slip into a mindscape similar to what you'd see in Mushoku Tensei when Rudy meets the Man-God, only it's between Slow and the reincarnated guy, with Slow saying he'd left Charlotte to him believing he'd create a happier future and that he'd eventually fade away, only for the man to respond that they should go together and they sort of merge at that point, right before the ending.
As for what follows, Slow tries to tell Charlotte what he knows and how he feels, but fails and is then caught up in all sorts of issues with the queen because he'd twisted the enchantments on the sword. Charlotte's left for days unable to even speak with him, and by the time they do speak she's beyond angry. Slow takes her to Huzac as a sort of apology, beginning a very entertaining new story. And it's only after this extended journey without much food that Slow slims down.
Frankly, this ending doesn't entirely make sense. There are still some huge obstacles standing in the way before Slow could realistically pursue a relationship with Charlotte, so him just declaring his feelings and her kissing him doesn't feel right. It's simply too soon for happily-ever-after.
