Fairly new myself....
There are a lot of differences between your sitch and mine, but thematically your experience and mine match up. She is expressing having given up, because to her there are some issues which she has tried to communicate to you in the past before but you have failed to pick up on. Whether she did a good job in expressing them before or not, is irrelevant. To most women, the right man "would just know", and she shouldn't have to tell you it should be instinctual. I will assume that at this point you still don't know what your issues are. Nothing to be ashamed of, I have barely started digging the surface in my sitch. In my opinion if she is this fatalistic she truly believes, she has given you a chance and you blew it. I bet you feel clueless about it too. So here is what you need to do:

1. Stop the self pity party, don't pursue relationship talk, don't beg, don't grovel. Accept the situation, at this point you can't come off as whiny or needy. It's not attractive, and if there is OM(not saying there is) he will just seem that much more desirable compared to you.

2. Validate her feelings, we men like to think we are logical beings. When both sexes are just as emotional and irrational. Her feelings are her reality, no matter how illogical or how much you disagree. Appeals to logic or reason, just reinforce to her that "you just don't get it, and you never will". You need to show her that you understand even if it means temporarily accepting things you don't agree on. If you can't agree at least say "I understand how you would feel this way". You'll find that once she calms down she'll be more logical. We call this state where the spouse seems to forget all reason and all happy moments "the fog" around here. It's a defense mechanism they build to help them detach. Only they can bring themselves out of the fog, any attempts by you will only drive them deeper in, and into the arms of someone that "understands them". Your first chance to validate her feelings will most likely be when she complains about you, accept the criticism use them to start positive changes. Which leads to point 3.

3. Start making positive changes. Start with the small things, clean up the house, groom better, excel at work, work out. WAW notice these things. Get a life (GAL) make her a little jealous (with out involving other women of course). As much as they may deny it women want super men.

4. Do 180's. Stop yourself ask what you would do in a particular situation and do the opposite, no matter how illogical it may seem. If she reacts well, or at least does not get mad where she previously would have, you made a success, and should stick to it. For example: I was always trying to be helpful, and could not understand why she would get upset. It was an independence issue, now I let her come to me. I know it seems to be contrary but it works. For angry men it means being more passive, for passive men it means being stronger. She already doesn't like you now so might as well try the opposite.

5.Stay positive!!! SMILE more! Look at the bright side of life. Do this mostly for yourself, and as a bonus your spouse may find the energy irresistible.

I have been at it for 2 months lurking around the forum and trying these, with what I believe is decent success. I still have some ways to go but remember it is not a sprint it is a marathon. When in this situation even the ugliest of fights or the most wonderful nights can be forgotten by the next morning, its just the nature of the fog. Keep working on yourself.