Guy's Behavior

Why does a boy want to appear that he was in a relationship and in fact he doesn't?

I think (Me) who I was chasing him and try hard to get in front of all boys and his friends and after a while he show interest on me but I ingored him and he start to chase me and flirt with me in front of his friends and he tell boys about me (I don't know what he say make them look at me all the time) sometimes act he care and sometimes he doesn't care at all and then I see he show he is sad and missed his girl (like he was in a relationship but he doesn't!) and at the same time I see he is chasing me or playing with me!! and talk to boys in bad way and never try to talk with me and say he want his girl who he missed; what that mean when a boy want to appear that he was in a relationship but in fact he doesn't?

Why does a boy want to appear that he was in a relationship and in fact he doesn't?
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