Why does my ex only post on snap when I post?

It has been a year since my ex and I broke up and he has a new girlfriend of about 8 months. I don’t post on Snapchat that often but when I do my ex always views it multiple times and then post a picture of his new girlfriend. If I don’t post on snap he doesn’t post. Why is he doing this? Everyone knows they are dating.

Why does my ex only post on snap when I post?
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