What if a boy says he loves you?

That depends. If you've been in a relationship with him, it likely means that he, well, loves you.

On the other hand, if you've just been on a date or two or none at all, he's likely trying to attach himself to you and cement a relationship. He probably believes what he says, but that may change as it's not based upon anything concrete. Basically it's a plea for romantic attention.

Putting it crudely, he could just be trying to get your knickers off.