Friendship

These past two weeks have dealt me a blow in keeping friendships alive. Two of my most important friendships I have been forced to abandon. A third has been put on hold. It seems that things always happen in threes. Either that or its just bad bad luck. When do you say to a friend that it's not okay to keep cancelling plans? Even if you miss them? Even if you feel like you would like to say it's okay, when clearly it's not? I just feel that it's so disrespectful to do that to people. And I can't for the life of me get past it.