Whats going on with him?

Me and my boyfriend have been going out for about 2/3 years everythings been great we've had alot of fights but always seemed to get through them. Hes now 20 and just got his own house and he hasnt beeen seeing me much or calling when ever we fight now he just huffs and walks away or hangs up and doesnt call back until i call him ... he phone me and told me him and his friends were going clubbing in mancester in the next few weeks i do trust him but i think hes gone off me he says he just busy, but to me it feels like he just doesnt care anymore i really love him and dont wanna lose him, I ve asked him why hes changed and he says he doesnt know what am talking about? Is it just me?