I AM that girl, just been with my boyfriend for three years, not two. And I don't feel disgusted when I do other things, I just would rather not. I like the simple intimacy of a really long, warm cuddle and hand-holding, things like that. Yet I love him more than I could say and am pretty damn sure we're going to be getting married when we're older. (Am Anonymous, JUST in case.)
I have a friend like you - as in, I may as well be the girl in your problem. I adore this friend of mine; whenever he's low he'll talk to me about it and vice-versa. We don't hug for too long, however, as for us I think that'd kind of be crossing a barrier too far. But our hugs are good ones, and we'll talk for hours about nothing and everything; I'd do anything for him, and he's said to me that he cares about me. Our feelings towards each other, though, are probably closer to brother and sister than boyfriend/girlfriend, though it has to be said that I do confuse the two sometimes and wonder if I do have deeper feelings for him.
But I find it doesn't matter; even if I do, I won't act on them for several reasons, including that I'm very much in love with someone else, I like that me and him have an almost-intimate friendship without there being anything sexual between us, and finally that I'm 100% certain he doesn't get the lines mixed up about our friendship like I do. I'm pretty sure he sees me as only a friend, always.
But that's all right. I love him as a friend, and that'll always be enough. So long as he's around, that's all that really matters.
So my advice to you? Stay the good friend for now; I know you like her and I know her feelings for her boyfriend are complicated, but making a move probably isn't the best idea. It's like me and my friend; if he ever did tell me that he had different feelings for me/kissed me/anything like that, although part of me would be happy, part of me would hate him for throwing something out in the open that could confuse my feelings not just with him, but with my boyfriend as well. (I'd still want to know, frustratingly.)
So basically what I'm saying is even though you want something more, it's not worth it. Just enjoy what you have with her now, because she'll always need you. When she argues with him or has a ****** day or anything like that, she'll still come to you. Yes, she'll have her boyfriend there, but there's something about having a close, personal friend that makes all the difference.
Just appreciate the intimacy you have with her now. I'm really sorry, I wish I could say "go for it, who cares who gets hurt?" but I honestly can't. She may be confused, she may love her boyfriend but doesn't feel very sexual towards him, but speaking as a girl who knows, it's not worth ******* up. Because even if I do get confused about my feelings for my friend from time to time, I wouldn't do anything about it. Because my relationship is worth fighting for.