What do u think is going on with my boyfriend??

i have been with him for 5yrs...we dont live together!!!!...he has not given me a reason to doubt him...but ever since he got a new job...he gets home very late and calls me till the fallowing day....i call his house and he is never there....he always acts like nothing's wrong when i question him about it.....oh and its every friday..i am tired of it....i sit around wondering about where he could be.....what should i do...he makes me feel like he does not care about our relationship!!!.....what should i do???