My friend is slowly turning on me and others, and she she's rude?

I've been really close with this friend for quite a few years. Last year we would hang out on the weekends and do things together. This year she has pretty much ditched all of her close friends, including myself, and is only hanging out with 1 girl. It bothers me and others because they seem to be turning into bitches. I get rude looks from them from time to time. She recently went on a school trip to disney world, and I joked that she should bring me something back. Not in a serious way at all. My friend who was also on the trip asked her why she had not picked me out a souvenir... And she said, Oh well she asked for one.. I found that incredibly rude so there is no way in hell I'm getting her anything. My friend was shocked because she knew I wouldn't demand a souvenir. Mind you she spent over 300 dollars on pins, clothing, stuffed toys, pens and pencils, and bracelets. Whenever I goodnight, love you! She'll rudely say ... of course you do. Or you better. Can't you just tell your friend you love her back? Often times I don't bother bringing a purse with me when i go out, and If I bring something extra along like a camera, I ask her if I can put it in hers. She always gets so defensive, saying that I need to get my own purse. My other friends don't seem to have a problem sharing there space. What do you think?