The line between friendship and love can often be blurred for both you and your friend. The question of whether men and women can truly be platonic friends has been studied by numerous researchers, such as those at the University of Wisconsin-Eau Claire who concluded that men and women view platonic friendships very differently. Men reported feelings of romantic attraction to their female friends more often than women reported attraction to male friends, even if both considered romantic feelings detrimental to their friendship. If you value your friendship but don't reciprocate his romantic intentions, dealing with his feelings may have long-lasting effects on your friendship.
Avoid sending mixed signals to your friend. The most effective way in which to communicate your feelings about dating to your friend is by being clear and direct. Although you may want to avoid hurting his feelings, unequivocally stating your feelings, or lack thereof, will send a direct message to your friend that you are not interested in dating him.
Look at how you're relating to your friend and determine whether your actions are sending mixed messages. This means you're going to have to look closely at your interactions and take a good hard look at your own behavior. Do you and your friend engage in date-like activities, such as going to movies or dinner with each other? If so, you may be the source of confusion within your friendship.
Allow your friend time to accept the reality that you are not interested in pursuing a romantic relationship with him. Don't expect your friendship to go back to normal overnight. Just as it took time for him to develop feelings for you, it will also take time for those feelings to fade. While you may not have romantic feelings for him, your inability to reciprocate those feelings may leave your friend heartbroken.
Encourage your friend to meet new people. Chances are that your friend has not spent as much time looking at his other options while he's been pining over you. Once the dust has settled, help your friend out by being his best wing-woman.
Accept the consequences of denying your friend a romantic relationship. Depending on your friendship, this may involve taking a step back to allow your friend time to get over you, or may mean that his attention will drift toward someone else who does share romantic feelings for him.