Weight loss/ relationship issues

I have a questions for all the Mama’s out there. I am having trouble losing weight… I have 3 beautiful kiddos. For some odd reason I can’t seem to lose any weight. Does anyone have any advice they can give me. I have a passed to the Y, I work out. I am getting super depressed about it. Also I’m having issues with my significant other he seems to think that its not his responsibility to give our children baths or change their diapers. He’s acting like a child. he is not helping the situation at all! He also refuses to take the kids to daycare with me and pick them up. We have been together for almost 5 years now.