A lof of guys make the mistake of asking the girl whether she is single. Most of the girls that go out to clubs and bars are, but they say they have a boyfriend. This normally means one thing – they are not attracted to you (yet).
Girls use this line to weed out guys they don’t like but also to test guys (this is called a shit test). If you react with “Oh! That’s a pity” and leave you’ve have lost.
Instead you should simply ignore this comment and continue with your routines. Just say cool as if she told you her name and start talking about something else.
Don’t mention her “boyfriend” at all! Suppose, she has a boyfriend and you start talking about him in any way (for example asking where he is right now), she will think about him and will feel uncomfortable.
However if you ignore the boyfriend comment and your game is strong enough she will forget about him: lead and she will follow! Trigger her emotions and she will be attracted to you no matter what.