My best friend doesn't seem to care about me?

I was born in Beverley Hills, and when I was like 2 my mom made friends with this woman who had a daughter. We would always play together and eventually got to be really good childhood friends. She's a little more than a year younger than me, and when I was five I moved away to Berkeley. We've been best friends ever since, and now I'm 15 and by now, her family is basically part of my family; I can't really describe how much they're a part of my life. But recently my friend doesn't seem to really like me any more. Whenever I come to visit her, she always says hi and gives me a hug, but then all through my visit she just goes online and watches TV. Whenever I suggest that we do something, or go to the beach, etc., she just goes, 'eh, don't feel like it'. She also has this big thing about space. If I'm sitting even five or six inches away on a bench or something, she'll ask me to move or scoot away. she also never gives me hugs if I'm down, even if I'm really in need (and say so), and just doesn't seem to really care about me. Now, she won't return my e-mails; I sent her one last month and she didn't return it, and basically sent one once a month and nothing. I wouldn't think it was a big deal, but last year and every year we used to e-mail A LOT. I just feel really sad about it. Any suggestions?