Body count

I recently got back with my ex and he asked about my body count. 18 after him (total 20) & he had 15 after me (total 21) so it’s 3 ppl difference in the time we weren’t together. Keep in mind it’s been 4 years since we spoken/saw each other so I believe it’s pretty reasonable for that number considering I moved on with my life and so did he obviously. But he is upset with me and says he won’t be able to look at me the same, despite him having one body more than me. Please help me out on 1: why does it fucking matter? 2: you have one body more than me total! 3: I don’t understand the issue??