Again. . . .

So apparently he started to talk to me again this summer..he tells my best friend about his girl friend ;he doesnt tell me…I asked him what he did this summer…he still doesnt tell me. we are pretty good friends we talk a lot . . . . I dunno why he wont tell me anything and I really like him…I know this because I can’t get him outta my head and think about him all the time for about a year…I dunno should I just move on I mean if he has a girlfriend then I really should just forget about him…but we have so much in common and im seriously falling for him what should I do?