Ex’s and uh ohs

Why did my ex go off on me whenever i hang out with my friends.. he thinks i have a thing with one of them AND I DONT, i don’t go off on him whenever he’s with his ex like idc but he gets all pissed off at me and says rude shit, FIRST HE TELLS ME HE LOVES ME AND THEN 2 DAYS LATER HE GOES APE SHIT and says i take everything back but ooo girl i know for A FACT HE MEANT EVERYTHING IN THE LONG MESSAGE HE SENT ME,... I’m just asking why he felt the need to go off on me when i was hanging out with my guy and girl friends