>>32 It's cool that you like her, but from what you're saying this girl is nothing but trouble. If she's going from wanting out of her relationship to wanting to stay in it forever, she's probably not someone you want to be in a relationship with -- I can smell the potential drama.
Girls are probably going to attack me for saying this, but you should probably distance yourself from her for a while. Not because boo hoo she won't date me so I won't be her friend, but because her saying "I love you" (I dunno about this girl but some girls will say that to anyone) and being so open with you is, correct me if I'm wrong, making you feel like it's more than "friendship"? （´・ω・｀） And it's likely that even though she's decided to "stay with her boyfriend forever", which it she'll probably change her mind about in a week from what I've heard, you'll still be hoping she'll come to you if you stay this close to her. Even if you WANT to just be her "best friend", it's simply not as easy as deciding to not have or ignore those deeper feelings. Usually it takes a really long time for them to go away.
Just take some time off from her, chillax, do some stuff to take your mind off her for AT LEAST a week.
Also, you should probably tell her how indecisive and confusing she's being. Though that would probably be a really hard thing for you to do.