I have actually been in a similar situation to yours. I was once engaged to a man I did not love, but he said he would kill himself if I ever left him. So instead of "hurting" him, I pursued other relationships with men. But eventually he found out about one of the other men, which hurt him much more than my breaking up with him would have. Also, even that did not make him leave me, so I did finally have to break up with him myself.

Now I don't know if you are feeling the same way I was, but I can tell you that in my case, even though I justified it by saying I didn't want to hurt him, it was really my own feelings I was protecting...I didn't want to do something that made me feel like the bad one. Even though cheating was a worse action, it didn't involve any confrontation, so it didn't make me feel as bad.

I think it is very important for you to thnk about why you cannot be happy with one woman, and why you don't feel able to leave a woman when you are no longer happy with her (from the way you wrote, you do not have much loving feeling left for your first girlfriend). Often, this involves some need for validation, from outside yourself. And there are things you can do to work on self-validation that can lessen this need.

But when it really comes down to it, the only way to change your actions and your behavior is simply to discipline yourself to do it. If you want to play the field, and see lots of women, that's ok...but it is extremely unfair (and possibly dangerous) for you to pretend you have an exclusive relationship when you don't. So you have some very hard decisions to make, and then some very hard actions to fulfill. It will be hard, because it goes against your natural inclination...I know this myself from experience...but I don't think you can work on redefining your relationship with women and with yourself while you are working so hard to maintain all of these pretenses.

Also, a therapist should be able to help you work some of these issues out.

Good luck, and I hope you can find your way to a more fulfilling life.

mj