Confession of an Engaged Retail Worker's Secret Nighttime Fantasy

I've been with my fiancé for years now. Everything feels perfect and planned out, our wedding next year, our life together. But there's this thing I do when he's sleeping that breaks all the rules. I don't understand why. It started as a harmless way to relieve stress after work, but it’s gotten more intense. I buy these naughty toys online and hide them in my room before going to bed alone. Then, once he's out cold, I let myself go. The fantasies aren't even about him, they're about being someone else, someone adventurous who takes risks. It's bizarre because during the day, I’m all about commitment and stability. At night, though, it’s like a switch flips and I'm this other person, experimenting with everything my partner and I would never try together. I feel guilty but also free while doing it. Why is there such a disconnect between who I am with him and who I become when he's not around? It feels wrong to keep hiding this part of myself from the only person who truly knows me.