She just wanted to make that hurt go away. Even just for tonight, even if he realised his mistake and smited her afterward, at least she'd have had this.
It wasn't clear who made that final move, maybe they both did, but their lips met and it was electric as ever. In spite of her betrayal, In spite of Lucifer, of what she'd done to Sam, Just right now she was kissing him, and he was kissing her back and nothing else mattered.
Her hands snaked around his waist as his own tangled in her hair and she pushed herself that little closer to him, deepening the kiss, never wanting it to end, but knowing it would. Still when it inevitibly did, he'd have it as a memory. So she was going to make it good.