Last year, I found myself in love with(still am, to tell the truth) a woman who I did everything under the sun for. I couldn't even begin to list everything, from house and yard work, doing stuff for her kids, some financial help, love and affection that she'd never had much of before, cards, flowers, e-cards, the works. People would probably laugh at me if I told it all. I literally spent all my time thinking of things I could do for her, and never enjoyed anything more.
We were crazy about each other, so it doesn't start the same as your story, but to keep this one short, the bottom line is that she's an emotional cripple with a huge amount of insecurity, partially due to a lifetime of bad decisions, and bad experience with men, plus a lack of love or affection in the home while growing up. Of course there's more, but that's as much as I'm going to get into, and that's enough, because it explains a lot of her behavior as the relationship progressed, from a total lack of appreciation or consideration, to accusations that all the things I did were just so I'd have something to hold over her head, etc.
She was beautiful, intelligent, sexy, and could be pretty funny, too. She's the love of my life, and still on my mind all day every day. She was my answered prayer, dream come true, and reason for waking up every day until she gradually returned to acting what I suppose is "normal" for her, which is a freaking psycho in my estimation.
Like I said, I'm still in love with her. Right now, without a second of hesitation, I'd kill for her, or die for her, but I walked away 4 months ago because she was killing me, and haven't spoken to her since.
I ignored a lot of red flags for things to go as far as they did. Some things I thought I could fix, others I thought enough love and affection could cure.
Our relationship did start out great, so maybe I have a little bit of an excuse(maybe), but you sound like you're forcing a relationship that doesn't even have anything going for it to begin with. I'm not saying that it isn't possible for someone to change, but you can't do it. You can help, but they have to realize what is wrong in their lives, and be willing to put forth a tremendous amount of effort themselves. Change is hard.
Just remember, it takes two, and you ARE supposed to get something positive out of it, too. If I want to do something totally selfless, that can't be repaid, I do it for elderly members of my family, or families that I know. I expect a lot more from someone that I want to live my life with on a day-to-day basis.