Favoritism!

Is it possible to like one child more than the other? Or even worse deep down if u do, is it possible to hide, without acting on it. I know the question is weird, and some may think how could a parent feel that way, but I have one child and one on the way. Lately my first born has been acting like a big baby he's 7 and cries all the time, whines, and I can't understand why. It makes me feel like I dislike my own kid? Please give opinions on what I should do, I hope everyone understands from my point of view. I love my son he's my world but he's been acting out lately and I don't know how to deal with it.