She sounds like one of those girls who is interested in "the best of both worlds". What I mean by that is she want the relationship pros such as, cuddles, cute day etc but she doesn't want the relationship status. She still wants to talk to other people and do stuff with other people. Girls like that aren't loyal and if I were you I'd meet up with her and tell her how it is. It's you, or him. If she continues to say "you are the only one"then just tell her to jog on. Girls like that are a waste of time

If you're secure enough about yourself you shouldn't care that she's talking to other guys. If you like her and she likes you, give it a shot. If it doesn't workout it doesn't work out, but she's going to talk with other guys who like her even if you go out so don't be possessive and dumb, just make a move and give it a chance. You'll never know until you try.