Sharing money

So me and my fiance have been having a disagreement. When we get married, I want us to put our money together but he wants to keep it separate. He's not secretive with his accounts or anything but I feel like when we're married we become one so everything should be ours. He says we can open a new joint account and put savings and bill money in it but he won't ever put my name on his other accounts. He says he doesn't want to have to check with me about making purchases and he feels like I shouldn't be entitled to money in an account I didn't contribute to saving. I feel like he doesn't trust me now. He is pretty well off and I'm not but I would never just blow through all that money. What are some benefits of just combining everything that I can point out to him when I bring it up again? Should we even be getting married if I feel like he doesn't trust me in this situation?