Most Helpful Girl
She's needing attention she knows you'll give her. You are good for her ego and she's likely using you to fill in whenever she needs a boost. She may or may not even realize she's doing this.
Most Helpful Guy
I wouldn't look too far into it. I would see if she can prove herself to be different from the last run around you had with her. Cheating usually with stem from a person's lack of communication. So, see if she can express herself clearly and in a healthy manner. The rest is really all on her. When I get burned and they come back, they have to do all the work to prove that they have learned from their mistakes. This is just my outlook on these things when they get difficult. I hope this works out for you.