I think it is because of the distance between you? How often do
you meet with her? Love without physical touch every now and
then(hugs, kisses, the feeling of knowing she can be there
physically when you need her) will cause a drift between the
couple, even though this might sound shallow to some, but it is
true.
Or it can also be caused by the fact that you have been with her
for quite a while now, I think every couple will go through the
period when the love settles and the initial passion fades away. I
remember one of the quotes I read somewhere, If you want to stay
for a long while with someone, you just need to keep falling in
love with that person over and over again.
Now that she is willing to change, I think just give her a chance
and see how it goes for a while. Try to do some things together,
try out some new activities to bring the spark back and to remind
yourself why you have fallen in love with her in the first place
If all else fails, if you really can't see her as
being the one for you, do let her know as soon as possible, in the
gentlest way...