Have you ever got to watch someone of the opposite or same sex masturbate to orgasm?
Even if it wasn't being done expressly for your benefit?
Did you get turned on and masturbate too?
In view of that other person or discreetly/privately?
My second ex claimed she masturbated thinking about me but would never demonstrate it to prove it. Just one of many reasons why in mid-2018 she become an ex.