It's a question I have also grappled with. I've been with my DH for years and we have two dc. He has had mental health problems throughout, we have had a lot of other pressures including dc with special needs, family bereavements, job stressors. He has also been emotionally abusive throughout our relationship - I am not perfect either and at the beginning of our relationship was very insecure and got upset easily about things. I've really worked on myself, been to counselling etc and feel a lot stronger and more balanced now.
The problem is, after all the things we went through I feel we are both a bit burnt out. I would have still liked to be close with him and feel like i do still love him, but my DH has told me that he doesn't love me in that way anymore - I think he sees me more as a sibling. He still wants to stay together for the kids, but I just can't, knowing that he doesn't really love me as a wife.
It's really sad but I'm thinking of leaving. So I think love could potentially come back in a relationship, but then again, if someone feels that things are too far gone, it probably won't.
I relate to what you are saying about money, if I leave, financially its going to be so tough. But I think we have to ask ourselves if we can really stay in these situations long term, even if we are financially better off is it worth it?