I Spy on My Sister's Love Letters

So there I was, sitting in my room late one night, and I heard a noise coming from my sister’s door. Being the nosy little sibling that I am, I decided to see what she was up to. Turns out, she had this huge stack of letters from some boy on her desk. My curiosity got the better of me, and before I knew it, I was reading through them like a total snoop. It felt really wrong at the time, but honestly, there were so many hearts and flowers in those notes that they made me feel a bit left out. After getting caught red-handed by her slamming the door shut, she hasn't spoken to me properly since. Now every time I see those letters tucked away under her mattress, I can’t help feeling guilty for invading her privacy, but also wondering if there's more stuff I shouldn’t be seeing.