Is this an 'emotional affair'?

No i dont agree. She may see you as just a friend rigbt now but an emotional connection has developed which means she could also be in denial about her feelings and lying to herself that you are just friends

but the reality is that even the bestest friends dont treat each other this way. They dont wana buy each other jewlerry or go for a meal alone together or spend hours talking on the phone etc.. Im guessing you dont do any of that with your male friends?

Its time to back away OP. Deep down you no this is wrong and you also no if you had a gf you wouldnt like her having a best friend like you.

Thanks again Michelle, I was just thinking of doing something nice for her but my suggestion was a little over the top! I sort of confronted her last night explaining how I felt and she got a bit angry and said something like "Can't we just be friends?". I told her my worries on the situation but she's more than happy to carry on talking as that's what she wants, nothing going on at all!

This could be called a love triangle, Anon, if this girl shared your romantic interest, but she doesn't. It is just easy and comfortable for her to speak with you anytime she needs it and maybe she enjoys having another male's attention besides her boyfriend's. The relationship she has with you is about her, not about you or you two. I'm sure you got this by now but for some reason you keep hoping that the day will come when she will start connecting with you at a romantic level. How much longer are you willing to wait when it's obvious she can't feel for you in a romantic way? Why don't you try to believe her for a change when she tells you that she only wants to be friends with you? That's all she can offer you and unless you give up your hopes for more, you can't be her friend either. Think about it like this, you waited and really tried, gave it your best but she can't respond to your feelings, accept it for your own sake and give yourself the chance to meet someone who loves you back.

I don't know if I would confront her, but maybe slowly try to drift away, and by slowly, I mean HELLA slow! Otherwise she'll notice!

Stop using terms like 'emotional affair'. You are too young. No, its not.