My Crush and My Silly Excuses

So I've got this thing for my little sister's friend Lily. She's just so kind and funny and every time she comes over, I make up excuses to be around the house too. Like last week when Mom asked me to help with dinner because she thought I was busy studying, but really? I wanted an excuse to watch them play in the backyard. But yeah, that's probably pretty weird. And it drives my sister nuts when I'm always trying to tag along or listen in on their conversations. She thinks I'm just being a clingy big brother. Am I totally off track here? Does anyone else do this with a friend of theirs? Is there anything normal about this?