Honestly, I hate to point to the guy right away because cumming takes two, like old saying goes, but in reality if your mind is there and your body has already done it, you clearly can cum.
So in my opinion, he just needs to up the tempo, be more aggressive (think Walking Dead), and eat that fucking (no Siri, not “ducking”) pussy like her fucking hates it, and for the love of God, DONT FAKE IT. You are not doing anyone a favor by doing that. Say “more”, when he hits that spot. If he isn’t sucking Tory clit and licking it hard, while spreading your lips to expose your clit with his left hand and his fingers inside you with his right (upward towards your G spot), just tell him to do it that way. When he makes you cum from oral for real – he will feel like a fucking Greek God.
Communication cupcake. That’s the key. No faking.