Why are you waiting for him to make plans/ tell you when you’re meeting up? Be assertive! Take the initiative to make plans! And when he beats you to suggesting hanging out, just say “great, I’m free at such-and-suck time. Does that work for you? You wanna watch that movie/ get lunch/ go for a hike?” You’re being too passive. And on that note: yes, mention to the guy that you were offended that he suggested hanging out on Monday, you told him when you were free, you reached out at that time, and he was doing something else and didn’t even seem to remember he suggested getting together with you. Tell him that you want to feel like more of a priority.