I can relate, I think we all can or will be in a similar situation in the future. I've been in a situation where I know its going to crash and burn, but I stayed with it, just to let it slowly eat my soul because I told myself that I wasn't a quitter.
What I learned for next time....if you need to bail, do it. It won't be worth it in the long run, you won't learn anything and you won't achieve anything. Any hurt feelings will mend in time, but who cares because you probably won't get anything from that partnership.