I suggest heading upstairs a few minutes early. Light a scented candle and dim the lights.
Lay in the center of the bed, with pillows propping you in a very comfortable position.
Put on a blindfold. Put in some ear plugs. Lay there for a few minutes before doing anything and just take in the silence...the darkness...the solitude.
Let your hands wander slowly, with no real purpose. Feel your body, and feel it responding to your touch. Your skin tickles, your nipples stiffen a little, and warmth slowly spreads across your body. Eminating from your core.
Eventually, your hands will wander to the moist folds of your most intimate of areas. Your secret place that you long to have serviced...to have worshipped. Your fingers will trace the outlines of your lips, relishing the slipperyness before beginning the achingly familiar dance across your clit. Soon your breath is roaring in your ears, and the darkness is interupted by the bright flash of your climax.
And your arms go limp by your sides. Your heart slows and your breath evens out.
A calm settles over you, and your tiredness returns. Don't fight it, just let it take you away.
With luck, you'll never know he saw any of it. You'll never know he was desperately struggling to stay quiet as his fist became a blur in his lap. And how he had to bite his lip to keep from moaning out loud when he came.
Until you slip in the puddle tomorrow morning.
Enjoy the night and report back in the morning.