If you’re just friends with benefits, why would he hide his story out with another girl?

We know we aren’t exclusive. So why go out of his way to hide it from me?
Updates
6 mo
Just have to update that it’s been alarmingly interesting to see how drastically different most of the female responses are to this question versus male. 😳 Women, y’all need to realize not everyone is out to get you. And I’m talking to myself in this too.
If you’re just friends with benefits, why would he hide his story out with another girl?
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