What I have done is have no secrets and set it up so that my spouse has access to my emails if he wanted. I have nothing to hide. I couldn't handle a relationship if we both had any doubts. I would not be able to handle that very well given the life I have survived. I would appear to be borderline (BPD) in that scenario, in some ways, with my lifetime of PTSD and the push-pull of needing to be loved (for once) and being afraid of being hurt.
I know I have issues growing up with PTSD for 30 years. I doubt Oprah or Dr. Phil would say to be like us, but this has worked for us and our trust and safety needs.
Frankly, just offering transparency makes people the opposite of curious. How boring is that? Why bother snooping if it's all out in the open?
What I asked for out of the transparency is that he occasionally might be asked to read an email first for me, to screen for triggering content. He has kindly agreed and has done this on two occasions with emails, when I felt vulnerable to attack by a sibling. He also screens the mail and when my narcissist mother sends unwanted mail, he takes it and holds onto it until he can tell I will be able to handle it, and then he shows it to me and asks what I prefer to do. I used to get the mail daily, until I had a bad year of abreaction flashbacks. He did not like seeing me so upset and broken. He's been willing to do so much on a daily basis to prevent my worst triggers. In some ways this has helped tremendously.
My husband is my best supporter and he is very sensitive to my emotional needs 98% of the time beyond what most people get in a spouse. I credit most of my recovery to him. My fear is that he will get tired of me and abandon me, or die. When the 2% of the time when he seems off line himself occurs, I can sometimes panic.
I don't know what your situation is really like. On the other hand, it seems to be sort of generally true that trust requires both parties to build up a system that makes the other person feel very secure all of the time. Trust is like a warm blanket in a cold world. Taking it off even for a moment sends a chill to the heart of someone. It needs to stay on all the time, for most of us, I suspect.
I'm not expert at all in this, just know that everyone is unique and has trust needs that must be dealt with carefully. I didn't understand that and did some damage in the early stages of my relationship.