Most Helpful Guy
From the guy point of view I can only say he want to get closer to you.
I have to tell you something, I was for a long time fooled by the idea that if a girl already as a boyfriend I shouldn't talk to her because it was pointless. But then I realized that at this age we are responsible adult and that at some point a we switch partner and maybe the current boyfriend of the girl I'm interested in has taken her from her previous boyfriend, etc...
Then I realized a second thing, and you could blame me for it according to your own opinions, I don't care, but what stop me from flirting with more than one girl ? Should I really go through an endless spiral of flirting with one girl>beeing rejected>flirting with another girl>beeing rejected... until I settle for an apparently stabble relationship. No, I flirt with a lot of girl only to increase my chances.
Just do what make you happy.