Messed with a coworker

I hooked up with a co woker and we were talking for like 5 months and only sleeping together for like two but it was just sex because we were both always busy. We would barely have time to even link for sex. But eventually I wanted a relationship and decided he wasn’t probably going to be interested. Now that i cut him off it’s been a month and he’s still gives me death stares and does petty things to me when i cut him off in a respectful way. I thought he wouldn’t really care because he was always so nonchalant about things but idk if this is normal behavior or what. I want us to be able to at least say hi but he always having a attitude whenever i walk pass him and gets jealous over me talking to other male coworker.