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Persons in the USA, Canada, and Australia use Google, Yahoo, and MSN search services often, and usually in that order by popularity.
Sounds like your dating site is based in Europe, no? If so, you may have a difficult time luring Americans away from the dozens of popular dating sites in the U.S. But it's always worth a shot!
I would suggest continuing to market like you have been, especially if your site is already listed in major search engines.