I think it's too easy to forget these people are strangers who have only met a few weeks ago, they are not in stable relationships nor indicated they are.
No one has even asked anyone to be their girlfriend, and for Rosie and Adam it's ten days, it's nothing, they don't know each other,
In that context Rosie went way over the top, full glen close, on a guy she hardly knows, what, because she wanked him off, cmon, she's 26, she should have held it together Better,,and had a bit more dignity,,not act like her long term partner just went over the side.