Increases his arousal level

She increases Mark's horniness a little, wanting to make sure he's already somewhat hot and bothered by the time she walks though the door. She waits a minute, so he won't make the connection, and walks in. Mark is in the kitchen, making pasta. He greets her cheerfully as she enters, the way he's done hundreds of times. How many of those times were after fucking my best friend earlier that day? she wonders. Still, she manages to hide her anger and responds in kind, smiling as she kisses him and tells him that dinner smells good.
"Ugh, these clothes are so uncomfortable," she says, unbuttoning her smart office blouse. She notices how Mark's eyes linger on her chest and her heart races with the knowledge that the app really does work. Mark kisses her neck eagerly.
"Fuck, you're gorgeous," he says. She giggles, playing her part.
"Someone's horny," she says.
"You know it," Mark says, groping her chest as he kisses her.
"Well, I'm going to get changed out of these work clothes," she says, smiling as she detaches herself from his eager hands and lips.
"Can I join you?" he asks.
"You can finish the pasta," she says coyly as she heads towards the bedroom.

She gets changed straight into pajamas. After all, she had to pretend it was a normal day, and it would be unusual if she went and put on lingerie or something. Plus, she didn't want to give him the pleasure of seeing her like that, at least not at this phase of the plan. She puts on a fluffy robe and moves her phone to the robe's pocket, but not before opening iCock again.