I read a fantasy novel in grade school around 2007. I think it was a standalone novel, not part of a series.
What I remember is the main character(s) enter a fantasy world. I have the impression they were human children/teens and outsiders to the world. Early on they meet a creature who is one of the last of his kind - in fact he might have thought he was the very last of his kind. He wasn't human but I believe he was humanoid.
They journey together to some place/city; I'm pretty sure reaching that place was the key objective of the protagonists. They reach it near the end of the book, during which they encounter a female counterpart of the same species. The creature wants to court her and keep their kind alive, but he is shy to approach her. Our human protagonists give him encouragement.