Need a girl's opinion on something...?

One of my friends has been hanging with this girl off and on for a while now. The relationship isn't going anywhere and I am now friends with the girl too. My friend has been getting mad at her lately and I look at it as my chance to get closer to her. We have been texting lately and i'm not sure whether she likes me in that way or not. Is there any chance she will want to hang with me more and forget about my friend (he isn't a close friend really). idk if it means anything but she always calls me jonathon when EVERYONE just calls me jon. is that a way of flirting at all? If you need more details then ask