Easiest way is suggest you both do it! Most women love the thought of you getting all horny for them too. So make an agreement that you’re both going to play, say three times a day, but not cum. If you cum there’s some forfeit.
Add to this when you’re together, don’t rush to orgasms, if you’re together for the whole day, just play and touch and lick her to the edge but tell her she can’t cum yet, you want her feeling like this till later. Then make her cum the first few times at the end of the night, cum… lots. But suggest, ‘how about we keep this horny till tomorrow’ and see how it goes from there.
You might try getting her to read this blog (hi if you are!) as you rub her or even better spend your time licking her clit. Of course you can claim you just SAW the question and didn’t ask it yourself but she’ll probably be more impressed if you just fess up!
And if you are the woman reading this try whispering, ‘I think I want try to being your denial slut’ to him. He might just blow his load upon hearing it (slightly ironically).