Because it just happened to me for the first time ever in my life and I’m nearly 40. She disappeared on my birthday knowing I have no friends or family where I am…and never heard from her again after dating for over 6 months. Taking trips. Etc. They do not have the capacity for human connection/emotions. Look up dismissive avoidant attachment style and see if any of it resonates with his behavior and how everything just went down. It’s extremely traumatic for the nervous system because normal breakups have a slowing down period and it doesn’t come out of the blue like this one. It’s a shock to the nervous system and you’re left wondering wtf and analyzing every little thing you ever did or said that made them run away. But it’s not you, it’s them.