MummyB I know the feeling. With hindsight I think it may have happened after the children and it's been a slow change since then or maybe it was always there but having children made it more apparent.
We are both going through v stressful times with DP illnesses/ death and maybe that's bringing it all to the fore. When DH DM died he came home and said he realised what was important, family was everything and he was going to change and be the best dad he could. This is now all forgotten.
4am no, it's not flippant at all. I agree, the very fact that I'm asking this question makes me think it is. Once you ask yourself this, it's hard to go back.
We had counselling after DD1 but we're back where we were before then, if not worse.
We're both tired and stressed but instead of pulling together we're not. We're just so different. Motivation, raising children, money when I look at that it's some pretty big stuff.
He struggles with the DC (which I do too sometimes) but I think that's part of parenting. There are so many good times with them which outweigh this. He never seems to see this, he doesn't enjoy the DC. He says that he probably wouldn't have wanted DC 
even though he loves them now.
I'll ask him to do something to help out for the family, for example we've got a holiday booked and there's one thing I asked him to do last week. He didn't. It's not a massive thing but it's what it represents. I ended up doing it last night, as it was essential and I feel resentful and let down. That he doesn't care about us.
DH says he tries to make me happy and I think he does, in his head, but he just doesn't give me what I need. We've talked but it's always the same. He pays lip service but doesn't change. And I don't think he will and, really why should he, that's him what right do I have to ask him to?
We always had a good sex life but it's got to the stage where I just don't want sex with DH anymore. This speaks volumes to me, it was always the glue that held us together, now I think it's just papering over the cracks.
At the moment he sees me as always moaning at him and he gets angry, so angry. I'm just so fed up with us both being miserable. I don't know how to fix it. Maybe it's me? Maybe we just can't make it work.
I just don't think it's bad enough to make the massive changes but then I think I deserve to be happy and if I'm not careful I'll be 10 years down the line thinking the same.
We have a lovely home, DC, income is ok. We should be so happy. But we're not. I don't know what to do.
Sorry this is a bit epic.