Before he leaves, let your friend know that you'll miss him dearly. Don't layer on the guilt by telling him that you can't imagine ever going to the movies again without him -- simply tell him that you've valued the good times you've had together and plan to enjoy the time you'll have with him before his move. Attempting to hold in your feelings will make you appear heartless and will do nothing for your long-term mental health.

Accept that you're going to feel sad after your friend moves. In a RealSimple.com interview, professor of psychology Robert Neinmeyer states that grief "can be a bittersweet beauty" and is "not something to be banished. It is a human experience to be lived, to be shared and to be understood and used." Acknowledge your feelings, and accept that the immediate pain will ease once you've gotten into the swing of things with new friends.

Make arrangements to visit your friend once she's settled into her new abode. Although it is possible to have a long-distance friendship, it is challenging when you are separated by many miles, notes psychologist Irene S. Levine in a February 2012 article in "Psychology Today." To keep years from passing before you see each other again, be intentional about saving money and taking time to visit your friend. If possible, make preliminary plans before the moving van pulls out of the driveway.

Once your friend has moved, resist the urge to curl up in a chair with a stack of cheesy novels and instead make plans to get out and meet new people. Use your friend's departure as a catalyst for personal growth. Not having your BFF around as a default dinner partner or shopping buddy may help you become more independent. When you get out and socialize on your own, you're likely to meet people whom you might not have met when you were engaged in tete-a-tetes with your best friend.