What would you do?

My boyfriend was talking about the downfall of him and his ex (it was brought up). So lets say my boyfriends name is Eric and his ex is Jackie. This is what Eric told me: Eric was friends with a girl named Sofia. Jackie was jealous of Sofia so she told Eric to stop talking to Sofia. Eric would get so pissed at Jackie that he would mess with Sofia on purpose. My issue is that he would intentionally want to hurt his (back then) girlfriend. Is there a new viewpoint to any of this? Is it even a bad thing?