Why did my ex block and unfriend me on Snapchat?

my ex and I broke up in December last year. It was mutual and we both ended on good terms. We were best friends before we dated and dated for about 2 months before major exams got in the way and we decided it was too much. We still talked after the break up , we still had banter and we still helped each other. He was always willing to help me and I him , of course most of the time it was school work related. We just finished a months long of exams and I haven't talked to him in about 3 weeks. We have never argued ever and it was all good terms between us. Suddenly today I noticed that he unfriended me on Snapchat. It hurt because I don't know why and because I thought we were good with each other. Any idea why? Did I do smtg? I could really use the help and advice.
Why did my ex block and unfriend me on Snapchat?
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