Every time you find yourself thinking about that cute lock of hair that brushes against his eyebrow or his charming smile, call to mind the time he asked you for money to help keep his electricity from being shut off or the night he stood you up at the piano bar because he was worried that his dog would be lonely. To allow yourself to continue to have feelings for this man is to court a lifetime of disappointment and likely financial insecurity. Make a list of the times he's let you down if you're having difficulty remembering.

As the old saw goes, there's plenty of fish in the sea, and many of those so-called fish are reliable, responsible members of society. Some of them are attractive as well, and there's bound to be a few you'll hit it off with. Remind yourself that if you continue to put your energy toward Mr. Flaky, you'll miss the opportunity to get to know some of these other men, most of whom wouldn't forget your birthday.

The only thing worse than having a crush on a guy you know is not right for you is sitting around spending all your time thinking about him. Take a mental inventory of the activities that you and the flighty guy like to do together, and then go and do something entirely different. Not only will you take your mind off him, but while you're enjoying your first efforts at surfing, for example, you just might meet someone more appropriate.

Focus on a role model, advises health psychologist Kelly McGonigal, Ph.D., in "Psychology Today." For example, you probably can't imagine your favorite actress putting up with a flaky boyfriend forgetting to pick her up at the studio after a hard day's work. Imagine that you're her, and think of how she would respond when such a guy texts her asking for a rain check on a weekend getaway because he decided to go fishing with his buddies. Follow suit, and don't look back.