In April 2013 my girlfriend and was having some cash/work problems. During this time I started to neglect my girlfriend. We talked about this but I did not change. I was stressed etc and withdrew into myself.

Then in November she slept with a guy 3 times but decided to give us another try. However, I could not get the thoughts of her and this guy out of my head and started to neglect her again. We talked about it but still I did the same.

Then in September 2014, she contacted this bloke again and is now seeing him. I know I forced her into this position by neglecting her and not being a true fiancé. I want to know if I can win her back?

You can't. She's gone and not yours to win back and any relationship with her will be tainted with the history of it.

There is nothing you can do that will convince her that you won't withdraw and neglect her when something happens in the relationship. You'll also never forgive her for cheating on you, no matter how much you tell yourself otherwise. "I could not get the thoughts of her and this guy out of my head...". That is going to plague any new relationship with her. It won't work and will end in tears. Again. You'll be good for a while and then something stressful will come up or a relationship issue will come up and you'll ignore her and it until she does something drastic about it. On top of that you're going to be forever trying to prove that you can change and make it work. This will put a whole lot of strain on the relationship as well.

This is all consider that she WANTS to get back with you. Which, by the sounds of things, she doesn't. The thing to remember is that you didn't force her into the arms of this other person. She did that on her own. You provided the conditions for it there is no doubt about it, but you didn't put them in a room with no clothes and box of condoms. She made the choice to sleep with this fellow instead of working out the issues with you. Maybe you didn't see it or maybe you ignored it, but she made that decision of her own free will.

Best option for you at this point is to walk away. Heal a bit and do a post morteum on the relationship. Then when you're ready, and only then, can you start looking for someone else. Don't chase after something that is dead, it will only lead to pain and tears. Take this as your wake up call.

As was said... move on, learn from your mistakes with this one. Some things can't be taken back once they are done with some people. And she is one of them, and this is one of those things many people just can't condone.. She has moved on, you must do the same now.

Too late guy. You are better served with making YOURSELF a better partner, with better behavior, and getting a fresh start with a better partner, who won't cheat no matter how badly you have behaved. You didn't care enough twice so nobody will believe another shot is all you need. She chose to cheat instead of dump your arse, so she is no prize either, so its no wonder two unhealthy people had an unhealthy relationship that failed miserably. That makes you both at fault, not just you.

Get a healthy frame of mind and let go of the sick excuse filled past. It wasn't love in the first place and you forced nothing on her. This is probably the best thing that can happen to you... getting dumped by a lying cheater. An excellent chance for you to drop the excuses and be a better person yourself.

Not really a chance, it seems, she gave you chance, after chance

You said, you could not get the idea of her with other guy, out of your head, you must have, or you would change.

You would not change this time, you only want your way, back.

Time to move on