AITAH??

Hey Reddit, I’m new to here. I’ve only had Reddit for about a month now.

For precautionary reasons I won’t be stating genders or ages but we are both adults with jobs. No children/ marriage .

I was with my partner tonight and everything was going fine as per usual, we haven’t spent a lot of time together in the past two weeks. They and I have been super busy with work and other things involved with family.

After enjoying some well needed us time tonight, I attempted to be silly and grab one of our adult toys out of the secret compartment in a filing cabinet, just to fling it around as a joke. (We often do random humorous things.)

However, upon doing so, I found two notes written on post cards that were unfamiliar to me. I picked said notes up and attempted to read them . My partner then asked what I was looking at and sprung up very quickly from their bed. They then grabbed the notes from me hastely, took a brief look at them, and began to rip them up right in front of my eyes and throw them away while saying "oh, those are not important." ( This whole time I'm just sitting here absolute confused and dumbfounded as to how they were behaving)

A little backstory, my partner and I have been together for about three years. We both know about each other‘s pasts and past relationships. We don’t keep things from each other, or so I thought. We love each other very much and have been through a lot together. Their actions during this altercation were abnormal and not how they usually would have acted. I let them know that I was upset and that the way they handled the situation was weird and made me feel like they didn't trust me.

My partner then went on to explain that it was from several several years ago, but didn’t remember what it was about or who for that matter?? I asked, "if it is from a long time ago, then why should it matter if I read it or not?" They then responded "idk, I just didn't want to be embarrassed." And to that I replied "You know I would never judge you, if anything reading the post cards would just help me understand you better and understand why you acted the way you did when I saw them." the room went silent for several minutes and then it became time for me to go home. They walked me to my car per usual, hugged and kissed me and I went home.

AITAH for thinking that something is being hidden from me and that maybe my partner is lying?