Recurring money issue.

Hello everyone im 25 and my partner is 35. We have a consistent disagreement when it comes to money. He's really bad when it comes to spending money and I'm the opposite I like to save since we have two kids together 3 and 1 year olds. I got my taxes back this year he keeps saying it's "our money" so he should be able to spend it because he helped make the kids, where I counter it with "no its mine"(<--only because I worked) or "it's really the kids". Now I'm not saying he can't spend it no but what I'm trying to make him understand is spending a little on yourself okay but spending 300+ on a app game is not okay it could have went towards to house, bills or the Kids. And that where are issue is not sure what else I should do? What are your guys thoughs?