I'm having the urge to be mean to her but I can't just bring myself to do it.
Why would you want to be mean to her in the first place?
She's just too nice, its really off-putting.
Well, I think it's a good thing that you can't bring yourself to be mean to her. She hasn't done anything to hurt you and you just shouldn't be mean to others, especially for no reason. I bet she has a lot of friends too because she's so nice and if you're mean to her you'll likely upset them too.
Nah fam I'm gonna be mean to her just for making me feel this way lol
There is going to be nothing good to come out of you doing this. If it bothers you that much, just have a conversation with her about it.