Sounds like you are in a bit of a pickle! I am not gonna play the saint and say I have not also been tempted to play the game but the fact is it isn't fair to either girl. Yes the idea of getting your cake and eating it to is good in theory but why hurt someone you really care about.........not even bringing into the light that this is just plain wrong. You know this and do not need a lecture from me about it other wise you would not be here in the first place.
The theory you do not want to hurt either one of them is a bit off..........come on if you did you would not have gotten yourself into this position in the first place. Sure you do not want to hurt one of them, but how is that fair to the other one?
Instead of looking at this as which one is better you really need to wake up sit down and do some serious thinking before this blows up in your face. You need to sit down and think about which girl is really the one for you. And then you need to act on it. Either which way you slice it you are going to hurt one of them......just do not put it off so long that you get caught again and end up hurting them both.
Sounds like your girlfriend was pretty understanding and forgiving of your first mistake......do not take that as a pass to keep cheating. While most women will forgive once few will forgive and keep loving you if you get caught again. At the end of the day are you willing to lose your girlfriend over this other girl? If not then it is time to stop, and I do not mean just with her I mean stop thinking about other women, stop flirting with other women and stop allowing yourself to get into situations that encourage cheating.
I understand the other girl is going to be hurt.........but the fact is you can not keep this going forever so eventually she is going to be hurt regardless. The key is keeping your girlfriend from being hurt as well. End it now and begin the real work you need to fix the problems with your girlfriend. That means biting the bullet and starting some relationship counseling. While your girlfriend may not expect it this will show her that you are ready to move on from the mistake you made before and want to prevent it in the future. (Thus strengthening the relationship with your girlfriend and learning new ways to prevent this in the future).
Look I am not saying that we never get tempted......we are humans. But everyone gets tempted, including your girlfriend the difference is knowing that even though we can get away with it we are man enough to not do it. Being a man is about more then just conquering in the bed........its about conquering in a relationship and being able to stand up and be a man for your women as well as yourself.
If you have any additional questions you can hit the reply button, otherwise please click accept so I receive credit for my answer.