YA book based around two teens looking for something

I don't remember a lot of details about it but it was a book series with one of them which I believe was called something to do with a harp? I know that there was a lot around this harp but I can't remember specifics.

The two teens were a boy and a girl who shared a few explicit scenes on their journey but I believe the story was more focused around the girl not the boy.

I believe it was an action book with strong aspects of romance as there is some fighting in it.

The harp is probably the most notable detail and I did assume it was the name of one of the books but I can't find it when searching?

I think it was roughly 3 books in the series and each book was 300+ pages This is very vague but I would appreciate it if someone could help!