As an adult you have to look at relationships with a little more depth then we used to and you have to look at your own self with more depth too. It may mean that you have to let go of a friendship that at one time were extremely important to you and you need to be okay with losing that friendship and not hang on to it just because its comfortable. It also may mean making a friendship with people who you don't necessarily love every aspect about them. A good friend isn't always the person you trust with your weird secrets, but may instead be a person who you just enjoy a specific hobby with or maybe just has a similar schedule then you. A good friend may actually be a few people who each hold one part of you.
You can't always avoid someone that you don't really like either. Sometimes you have to smile and just deal and make the best of a situation that you wouldn't normally put yourself in. I struggle with my own principals when I am put in situations like this. I want to be an honest person, I never want to be considered "fake" to others or feel like I am just acting like I do at wok. When I am in a setting where I have to smile and deal and its not work, I really feel like a big faker. But spending time with someone you didn't think you liked is not necessarily being fake, its understanding that just because your ego decided something about another person, sometimes you need to put on your big girl bloomers and realize that its just your ego talking and grow up and look past that. Being genuine and honest and not fake, also means you have to be kind and empathetic at times.