AkioMaster
She's insecure and realizes a relationship isn't something that is good for her right now. Maybe she thinks the two of you aren't as compatible as she originally thought and wanted to try to end it in a "nice" way. You can have feelings for someone but realize they aren't a good match for you.
"Staying friends" is a way to to *try* to avoid hurting feelings. People (not just women) sometimes use that excuse because they think it's easier to wean themselves off of a person, rather than completely cut them out right away. Sometimes it is, but a lot of the times it just makes it worse. And some people legitimately want to stay friends.
The first sensible response here. More than anything she's insecure right now, OP, and doesn't feel comfortable in a relationship. If you were to take it personally- which would be unfair to yourself, given that from what I'm reading her reasons have to do with her, personally, and not you- she's a touch intimidated by you, not BECAUSE of you but because of her feelings about herself when she compares them with what she sees in you. She feels unworthy, if we oversimplify things.
I've definitely been here, OP. With my fiancee (I'm 24). You don't have to like it, but in the end it is their choice and she's got every right to do what she pleases when it comes to relationships, even if she's shooting herself in the foot again and again. My fiancee had commitment issues and I expect will continue to have them with other people, self-doubting (self-doubting what exactly she herself couldn't put into words for me at any point in our long, long relationship, but I think she thought she'd be unhappy 'in the end' like her aunt, whom is a serial wife, divorcing left and right). Best of luck to you, and I mean that honestly. It's a fact of life that people are a sort of buffet, each individual having their own pros and cons, so that we might genuinely be happy with one person or another but have a different life altogether because of who that person is. A different life, not necessarily a better or worse one.