My boyfriend gets angry if I make plans with friends or family

If I invite a conversation about what seems rational, he obfuscates and becomes cross. I’m very confused by this. Recently, I was trying to help my mum plan an outing and asked his opinion about timings, and attempted numerous times to sketch out a rough structure for the day, but each attempt was dismissed. We had several attempts at me trying to triangulate between two parties and I always came away confused. I try to be open and accommodate all ideas.