What to do when he doesn't call when he says he will?

Urgh! This is so frustrating. I would just like for my boyfriend to call and check up on me just to see how I'm doing. Since he still hasn't called I'm contemplating just telling him I'm busy this week so I need some "space." He usually spends the week with me cuz I live on campus and goes back to his parents on the weekends. Is this response passive aggressive, probably. What is the assertive thing to do here? Thanks for your time.