you sound like my boyfriend.. he is going to birmingham uni this year.. meh.
i always think that he doesn't want to see me, be with me or spend any time with me.
i'd just love it if he just let me know that he was thinking about me, even just texting me saying 'i love you'... that would be enough. he does do this most days too.. bless him.
it's hard to tell someone how much you love them. i know it is, because i can never tell my boyfriend enough or find the right words. even when i do, i try not to say too much because i think he will get sick of me and start hating me or something.
all i can suggest is that you constantly reassure her. maybe she is like me and needs constant reassurance that you still love her and want her.. as nenna suugested, a nice long email, or had written letter would probably go down really well. that way, she has something to look at even when you aren't around and it will remind her that her boyfriend is thinking of her. me and my boyfriend exchanged letters before i went on holiday once.. i remember reading that letter every day while i was away, and it just made me rememebr that he was at home waiting for me, thinking about me and missing me.
i'm not sure buying her anything would show much.. i think a letter is a good way to start at least.. send it in the post and don't tell her about it :P it will be a nice suprise when she wakes up one morning.