Boyfriend advice ?

Me and my boyfriend have been together for 2 1/2 years , everything is great , but lately he don't reply to some of my mesages or atleast takes a couple hours to do so . I understand  when he's working and he can't but on the weekends it's the only days we can see each other , so yesterday we had this dry talk and he never replied back , but yet he gets on Facebook and stuff . I don't know what to do. It seems to me like he's not interested anymore .