True, they have some great acting skills but I don't think she faked much here. It seems like she just got very worked up. She was damn eager to suck his cock. If it was staged I think she would've have let him fuck her.
I start to get the feeling that a lot of acting talent funnels into the Japanese porn industry. These actresses are phenomenal. Or she had a very real orgasm watching the other guy cum because watching her eyes light up like seems so hard to think she faked that.
Failed to fuck. Make her more high n horny then coax to fuck, will have higher chance. Rub her pussy, then insert finger n finger fuck, she will slowly be used to it and then high chance to fuck her.