Imagine going to the movies, a restaurant, a concert, or whatever place people use to gather and socialize. Then, you take out a cell phone-sized device out of your pocket which tells you which (girls/boys) in the place do have a (boyfriend/girlfriend), and which ones do not. So, you rule out the engaged ones, and begin looking among the single ones one that is attractive enough for you and start a conversation. I could certainly give some use to something like this - anything to avoid the dreadful "Do you have a (boyfriend/girlfriend)?" question and the subsequent fear of rejection (or worse, a potentially embarrasing situation involving his/her significant other). In the meantime, until technological progress catches up with us, we'll continue to be exposed to the hit-and-miss routine...
Anyway, just a thought.
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"Many people would rather die than think; in fact, most do." - Bertrand Russell