Would you feel cheated on if they fantasize about someone else they'll never have?

They're fantasizing about someone they'll never have. In my case, it's my BIL (brother-in-law) that I've always had a crush on since I was 12 years old. Unfortunately my sister and him are 3 years older than me, they dated in HS, got engaged later, married and have kids.

However, I've kept old journals about him. We never ever had any contact other than your typical hello family greeting. He only has eyes for my sister, no one else. I'm realizing that I'm really in love with a fantasy I'll never have, I don't know my BIL very well like my sister does and yet kept that secret to myself.

If I were in a relationship and you found my hidden journals about him (my fantasies about him), even though nothing ever happened, I'm physically only with you and it's all in my mind, would you feel cheated on?

Would you feel cheated on if they fantasize about someone else they'll never have?
Post Opinion