Rather as March-Hare says, the relationship may well be genuine, and feelings mutual. Alternatively he may just care for you as a student like you say, but that's not worth worrying about.
Either way, the law is clear, here as well as in the US: sexual relationships between teachers and their pupils are illegal as long as the pupil is under 18. In itself that is reason to be careful.
I wouldn't want to say that you should stop contacting him, but make sure that until you are 18 the emails go no further than they are at the moment. After that -- if he likes you and you like him and it works out for both of you, then why not? But if you would never do anything to risk his career, then I'd try to push this out of your mind as long as taking it further may well do just that.