Everyone is thinking about Chloe's faces during the webisode The Journal. Why? Because a lot of people think that she has trouble making friends and she felt left out. Or maybe it's because she has a mom somewhere and it's missing like Adrien's mom, or maybe they have the same mom! That's why Adrien doesn't want to kiss Chloe.
I'm just mentioning what everyone is saying and what all theories are out there, and I added a little theory of my own.