Take it from every perspective you can. From your point of view, they're fake because they act differently around you and others. They lie to you but it's a different story for someone else.
If you look at the person who is "fake". You can maybe see if they are trying to protect something. Maybe protecting themselves. Hiding something they don't want you to know. It could protect you sometimes.
But you shouldn't really care about others actions. Just be yourself and its all that matters. :) Hopefully I was helpful. Good Luck!
I hate having to act fake as well. If you don't want to know how someone is then don't ask. I hate it when I ask how someone is or has been and they just say they are fine. No real person is always fine. I have social anxiety but being expected to fake being so "FINE" is a bunch of crap to me. I love people who just let it all hang out. They are so real to me and I love that.