Listen to your heart, I'm sure there's one you want more. Which do you think about more? If you're finding it hard to decide make a list of pros and cons for each and another list of thinks you want in a girl, it might help. If you want the first girl, since she already likes you give her some time, I'm sure she'll want to be with you in the future. If you like the second more, tell her! If you still can't decide, its not bad, you don't need to feel guilty... it's human. Plus you're not with either you just like them both. Good luck!