If you love her, leave her alone.
I know the concept of this is ultimately painful, but you have to weigh up both ends of it.
For one, she's 10, and is therefore hardly capable of knowing what she wants from life yet (because she's hardly experienced it!). Pinning her down into marriage for your benefit would be wrong, because even at 16 a person is still majorly inexperienced.
As for the age gap, you clearly know that you are a paedophile. You may enjoy being with this girl, but a desire for anything erotic is dangerous. I'm not condemning you as a bad person, because people can't help what they feel - but they CAN help what they do.
You need to break ties with this child and cease to view her as a potential mate, because she simply cannot be.
In time, if you continue to be part of this child's life, then who can predict the outcome of your relationship. All we know is that any relationship above the platonic level would be innaproproate at this time, as the child is merely a decade old, and will not understand many of the emotions or desires that you, or any other adult, may feel.
Leave her alone, to save her from yourself.