How can I ask if he’s seeing someone else?

So I keep asking this guy if he’s dating other girls or flirting with them and I can’t get a answer I want. I first asked him if he was seeing another girl and he says yes he sees girls everyday, they are part of Earths population. Im just wondering what exactly to ask him to give me the answer im looking for.
How can I ask if he’s seeing someone else?
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