Imagine the joy of finding the mental spot to not be bothered by sexual attraction with someone you (realistically, as much as she has vented to him they have known each other for what's been implied to be 7 days - the night he arrived at fukuoka, and the week he just finished working) barely know and is very attractive, enjoying the comfort of friendly interactions with them to the point that even with some romantic/sexual tension you can enjoy this level of skinship in a relatively chaste manner.
God how I hate my libido
BTW, reminder both of them are each other's emotional support, to an extent. He is in a place that's basically foreign to him, and she's turning herself into mulch between her lifestyle and the effort she puts into her work - while being STARVED of companionship. Not sure if "sleep over at someone I met last week" starved, but with the joke being what it is I guess I can give it a pass (doubly so with the nuzzling and petting at the end - being less sexual and more affectionate).