Is this wrong?

Chicago IL

Description

I'm involved with a woman, but it's long distance so we don't see each other often. I've been faithful to her, and I don't have a desire to be with anyone, but I just miss her so much, and recently I looked at her sister online. Her and her sister are opposite as far as body type, but me knowing it's her sister, it arouses me for some reason. I'm wondering if I should feel guilty about this. For me I just miss her so much, so I've looked at her sister a couple times. I have no desire to me with her sister though. When I look at her sister I see the similarities in their faces, but as I said, I don't have any desire to do anything with her sister. Do you feel this is normal, or understandable? Or have I gone too far?