my ex bf was like that...so there are more and more misunderstandings between both of us. end up we broke up. but as a "spectator", wat i can say is....in this case, i think he doesnt hide anything from you. he shows you his mood but hide it from his frens. if he talks a lot with his frens and makes you feel uneasy, don follow him next time. just stay at home. if he doesnt want to tell you, don ask him, give him ur support silently.