Step1 - Re-evaluate your expectations of your friend. Sometimes you experience feelings of disappointment because you set expectations too high. Ask yourself if you're being realistic about the friendship. Maybe your friend is too busy to hang out every, single weekend. Be sure you are not asking too much of your friend.
Step2 - Talk about your feelings. Handle your disappointment with clear communication. Your friend cannot change his behavior if he is not aware of how it makes you feel. You'll feel validated if he acknowledges your feelings.
Step3 - Be understanding. Your friend probably did not mean to cause your disappointment. There may be stressful events happening in your friend's life that cause her to act that way. Understand that everybody makes mistakes now and then. Handle your disappointment by not dwelling on them. Forgive your friend and move on.
Step4 - Look for the lesson in the difficult situation. Every disappointment brings an opportunity to learn, even when it's caused by a friend. Looking for the lesson helps you transform negative feelings into something positive.
Step5 - Keep your perspective. Your disappointment may seem like a big deal right now, but it may not be. Ask yourself how much the your disappointment will bother you a week from now, a year from now and five years from now. This helps keep minor issues in proper perspective.
That a lifetimes not too long to live as friends.