B.B.
I can understand why you are upset, but not to the point of considering leaving him over this. When I read this, yes, alarms went off in my head that he's hiding something. But, he could just want something that's his. Maybe he feels like everything in his life is shared, so he wants something that's his. Maybe it is something more, but you'll never know until you talk to him. I suggest, like some other posters, to calm down, then talk to him. It helps me to write down exactly what I'm thinking before I talk to someone when I'm upset, so it's more clear in my mind exactly what's bothering me about the situation. Are you upset he wouldn't let you use it? Or do you think he really is hiding something? Either way, just talk to him as calmly as possible, and let him talk also.