Him, my ex, me and one another were a close knit group. After the breakup, is when he and ex got real close, but would say I'm overthinking whenever I pointed it out. Eventually, the bond broke when it was revealed that most of our one-to-one talks were shared with my ex (despite me keeping a lot of his stuff a secret) and him constantly prodding me to apologise and give ex some "peace of mind". He also did a full 180 of his lifestyle on ex's suggestions (when weirdly, I had been judged by him for suggesting the same few months prior to the rift). They cut me off from their group but hey, met a lot more people (and formed more friend circles since) and am currently in the best state of mind creating amazing memories