I don't like my friends relationship choices
What is it about your friend's choices that you dislike?
I think you don't have to commit to a relationship
Your opinions on relationships shouldn't be applied to your friends. They should get to choose what they want to commit to.
My friends are being selfish by choosing to commit.
It's understandable that you have a different mentality regarding commitment. However, you should respect the choices that your friends make regarding their relationships or you will seem like a negative friend.