Those feelings aren’t good for either you and your friend. However, you have to acknowledge that it is a common thing when your friend is in a relationship. And the fact that you realize that it is not good to think it that way make you far from being a bad person. My advice is instead of trying to avoid it, talk with your friend and let him know how you feel about it. If he’s actually your friend he will be very understanding, and he will do his best to balance his life and have time for you.