Am I crazy or am I crazy?

Why is it that right before I get my period I always get very suspicious of my boyfriend. Like I think right now he has a thing going on with a girl at his job because he left work an hour after closing yesterday . Even though things have been good between us maybe he's bored and has his eyes on someone else. I don't want to bring that to his attention in fear hell think I'm accusing him but seriously tomorrow's are 4 year anniversary and I feel like he's been with and mentally interested in someone else I just don't have proof .😔 advice?