Once, it must be 2 or 3AM, you wake horny and frustrated, and you hear her.
So you ask if you can help out.
She eagerly lets you eat her out, and you give her two orgasms.
You enjoy it, and you hope will earn some reward.
But it doesn't relieve your aching need at all, and in fact just inflames your sleepy passion.
Also, you can see and feel how turned on and wet she is, and this makes you start to worry a bit about her plans for the day ahead.