What should She do about the other guy?

Okayy, so my friend (lets call her Bob^-^) Well, Bob has been going out with this guy(let call him Charlie) for a couple months now. Before Bob and Charlie went out, Bob had liked this other guy(lets call him Jason) for awhile. Jason hadnt known Bob well so they started to hang out sometimes. Bob had ended up asking Jason out, and Jason said no because there was a slight age difference(3years). About a week after that Bob and Charlie started going out. Just last week, Jason has texted Bob,and they ahdnt talked in about 2months. Jason and Bob met up, and had kissed, and now she likes Jason again, but still likes Charlie. Jason also has s girlfriend. So what should Bob do??Please Help(: