Woman's Intuition, is it real?

We've been together for a year now and we are currently in a semi-long distance relationship (two-hr drive distance). There's a feeling inside me that he is cheating due to some changes in his mood, sex became lesser, he would just ask me out only once a month now and sudden meet up with his friends every night became frequent which are way too late. It's like i'm with a totally different person on how he treats me now. Are guys like this after a while in dating? When we started, it was like he was the effort kind of guy then he suddenly transforms like this. Should i trust my intuition and confront him that i feel like he's cheating on me or i'm just hormonal and overreacting?