Me and my fiance do not agree on how to raise our son, I'm afraid this is ruining our relationship.?

My son is 8 months and as much as I tried he will not eat the jarred baby food, therefore I have introduced regular food into his diet which he loves...meun would be cream of wheat, soup with very soft noodles, regualr fruit mashed up and pieces of meat. Now I spoke to the baby's doctor and a nutritionist who said my son needs to eat and the things that I give him are fine, they even suggest I stop mashing and grinding up everything. My fiance is always complaining saying my son is not ready, I'm moving to fast, he should be eating pureed food etc...I explain to him what the doctor says, nutruitos, other mommy's, book and even my own expericences with my son but he still thinks he is right. My fiance never bathes my son, feeds him. puts him to sleep or anything...I'm usually with my son the most. When I try to tell my fiance things about my son or what I want to do he always shoots it down. I don't know what to do, my fiance has a son from a previous relationship is this why?