Hi Alex,
This guy may have never broken up with his girlfriend because he still loves her.
He may have told his ex girlfriend that he is going to break up with his current girlfriend because he may not have been happy with how the relationship was going.
Perhaps he felt as though he got along a lot better with his ex girlfriend when they were in a relationship.
He may have even had some recent arguments with his current girlfriend that led him to become even more upset with her.
However, he may have never broken up with his current girlfriend because they may have started getting along a lot better and she may have started showing him a lot more affection than he is used to from her.
As a result, he may have chosen to stay with his current girlfriend because he has gotten comfortable with her and doesn’t want to take the risk of breaking up with her and coming to regret it.