She longs to take control of him... of his body. Likes the idea of making him powerless to her desire. Wants to do things to him... please him, while fully in charge.
He's taller than her. Much stronger. So she wouldn't be able to achieve this through brute force. It wouldn't be possible for her, to say... press him up against a wall... or push him down over furniture. Meanwhile with little effort on his part, he could pin her (if only he would) or manoeuvre her in any way he pleased. So in her imagination, the way she sees it happening is with his agreement to let her do her bidding... also, hell why not, some playful hand-restraints.
To be clear. She doesn't want to take advantage of him. Or do anything without consent. She just... wants to dominate him a little. Tame the beast, who in his real life, is typically the one to take control.
Part of the issue here, is he doesn't belong to her. He is not hers to take. They are "friends". She is "married". But lately, when she lays down to sleep at night, he keeps filling her mind's eye. And she's overcome with a desperate longing to touch him.
She imagines taking him to a hotel. Leading him to a prepared room and telling him to let her take the lead.
After swiping the room key, she'd take him in. Then push him up against the door and press her body against his... pausing to feel his breath, his warmth. Without warning, she'd slip a hand down over his pants and stroke his off limits cock.
Feeling it twitch against his briefs, as it started to engorge with blood, and desire... she'd lead him to the bed and push him down. Then climb on top of him and pin his arms back. One at a time, she'd tie them to the bedposts with a waiting rope.
She'd take her time exploring him. Stroke his face gently with the tips of her fingers... feel his facial hair with the back of her hand. Maybe slip one finger into his mouth, for him to suck. She thinks she might like that. The feel of his soft wet tongue pressed against her index, or middle finger. Possibly both.
She'd lower her face to his and brush her cheek against his beard... then bring her lips right above his, and hover there. She'd wait... wanting to savour the moment. To be fully present when her lips met his. She knows (don't ask how) that they'd be soft. And that when his unpredictable tongue met hers... it too would be soft.
She'd take this part slowly. Feel not only the soft, wet, meeting of their mouths, but also the way that connecting with him would send a ripple of excitement through her. Maybe even make her a little wet some place else.
Curious, she'd slip her hand down again. To feel his cock through his pants. See if it was hard. Exactly how hard.
There's little she likes more, than the feeling of a hard cock in her hand. The more firmness she meets, the more excited she becomes. And the feeling of him... his cock in particular, would erupt in her all kinds of desire. Worth noting, she'd be very tempted to undo his pants at this point. But would hold off.
Instead, she'd pull up his shirt. Take in his chest. A chest she longs to lay against. Longs to be comforted with. Longs to lean on, while being read to. A chest that houses his (in her humble opinion) untended heart. She'd kiss that chest above his heart.
Then lick, suck, and gently nibble a nipple or two.