She says she needs to stop thinking, stop her mind from working, keep all the thoughts that haunt her away. She comes to you for help; says you've dealt with darkness and know how to block it out. You try to come up with distractions, teach her your breathing routines, calming down techniques... but it doesn't work. The Dark One is stronger than anything you've had inside you, and it does not want to be silenced.
She begs you, though; for help, for a few moments of peace inside her own mind, for rest. Seeing her cry out breaks your heart; so you try something else as a last resort. It isn't appropriate and it might make things even messier, but she doesn't object when you suggest it, so you tell yourself that this isn't sex; this is just a means to an end, a favor to someone who's given up on everything she had for you.
You make her lie down and sneak one hand around her waist for comfort, and the other between her legs. You work her up little by little until she's at the very edge... then stop. She protests, but you tell her to trust you, you know what you're doing. You repeat that process incessantly, until her protests turn into pleas, pleas turn into whimpers, whimpers fade away and all she can do is stare at the ceiling. And you know, from her glossy eyes, that it worked: she's not thinking at all at.