Or as Wendy Cope put it:
2 cures for love:
Dont call, or ring or even send a letter.
The second?
Get to know them better.
A little bitter perhaps, but to the point. If you are smitten and they are not then it will not end happily. So backing off until they are out of your system would probably be a good thing. Remember if they are with somoeone and you preecipitate a breakup, at some level they will hate you for it. Men in similar situations often indulge in "Sh*g Therapy"...a string of meaningless sexual liaisons to take their mind off it. Which tells you something about the location of mens minds. But the basic idea, of getting on with your life somewhere else, is a good one. Get out there and soak up some culture, meet new people, enjoy life. If they are worth moping over they will come after you. If not you will be too busy to care much.