More broadly: is fake happiness still happiness?
Can you give me an example of fake happiness? Do you mean when you pretend to be happy? Then no, fake happiness is not happiness. But I'm sure you already knew that. You probably also knew that pretending to be surprised is not the same as being surprised.
And to answer your first question, that depends. Sometimes it is better to be hated for who you are, and sometimes it is better to be liked for who you are not. In fact, it is often the case that I'm liked by a boss for things which I would say, outside of the business world, I am not. But, I make sure that my boss continues to like me since that means I get promoted faster. In terms of romantic relationships, personally, I advocate being who you are, that is, not deceiving.