Did something happen to you recently that involved you and your sister? Possibly something traumatic? That could trigger the close feelings you have been having. I strongly suggest you go see a therapist to try and figure out the root of your problems. A lot of times, these things have nothing at all to do with sibling love. You might be avoiding something else completely. Did you recently have a bad breakup? Your sister is a "safe place" to let your feelings reside. It's all psychological. You KNOW that she wont reciprocate so it's safe to like her. You know you wont get hurt by her because she is your sister. I really think you need to see a specialist though and get to the bottom of this. It is not healthy and you are risking ruining things with you and your sister on a family level. Just get help. Nothing wrong with asking for help.

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