To me this translates a bit like... "I like you. You're my friend. But there is someone I like, enjoy the company of and value the friendship of a whole lot more than you."
Yes I realise this makes me sound like I'm still in school, I'm not, but I do find as an adult when my friends tell me about their best friends, I feel a little sad that I don't quite match up. I'd never say anything obviously.