I have a question and maybe yo

I have a question and maybe you can assist. I have a cosigner on a mortgage who is my exhusband who I remain friends. He is also considered to be the "coborrower" on the mortgage. Our lender is stating that we both "intend to occupy" the home and he will also be on the home owner's insurance. In both cases he will be considered as primary resident of the home. Here is my question. Why is it that he has to be consisered primary resident if he is the cosigner? I thought I made it clear when we applied for the initial loan application. Seems things were more informal then terms kicked in as all of the paperwork started. My ex inherited a home where he currently resides, has home insurance as his primary residence and our 2nd home where we lived as a married couple which he plans to rent until he sells. So he currently owns 2 homes. I wanted to purchase my own home and he was just going to help me with cosgining etc. Now it has turned out to be a much bigger deal. Is there anything we can do to clarify? Are all Lender's the same way with the cosigner terms? Any advice or suggestions would be helpful. Also, do you know if I can put my name only on the title since in reality I am paying for the home 100 percent, and I will be paying half of the house price as down payment going in.