I was once like your girlfriend. And let me be blunt, once you let her do that it will NOT reassure her AND it’ll make her think she has more control over you. She’ll think since you gave her the ok that she can do it all the time. She already doubts you and doesn’t trust you. After she reads them she will find another thing to question you about. Her behavior isn’t okay and accepting it will only make it worse. You need to be blunt with her, she either trusts you or she doesn’t. She can decide to communicate with you more effectively without crossing boundaries, or she can leave. You can also decide to leave, which I would highly recommend is she’s being closeminded about the whole situation.