Of course! But not cumming is usually hotter than being allowed to cum. Being kept in that desperate, wet, insanely horny state, the feeling of euphoria sliding over your skin like invisible hands, only to discover your hands are following it.
Why, when you can feel like that all day, would you want to cum and lose it all for just a few seconds of pleasure?
So yes, I do let them cum, but they don’t usually want to, so I just give them what they want.