Well that's a positive about him wanting to parent his children. The disparity in wages is an issue for so many families, together or not and so many women have no choice but to sacrifice career progression resulting in lower pay grades often for the rest of their life. You both made the decision to become parents and so both must share the responsibility of financial support but more importantly of being a good parent. I am glad you seem to at least have the latter sorted. Having said that I still believe that all arrangements should be binding. I say this because I have witnessed so many marriages end with a cooperative and responsible parenting commitment and then some other influence (third party) enters the picture and the arrangements become like the house built on sand. Build it on rock and that will at least help to ensure compliance even if a new influence doesn't want it that way.

Best of luck with it all.