Help, please, divorce and children issue?

Last night my dearest friend came over to my house after having dinner with her significant other and his one child. They have been dating a little over three years, and it was a bad divorce, apparently. Of the children, two wanted not to meet my friend, and the other was not opposed to meeting her, so finally did. The one that met her is the oldest who is home from school. Over the course of spring break they went to dinner twice. Both times it was pleasant, she said with most of the talking and all of the questions happening because she asked. Her boyfriend was elated as he had wanted to start bringing his two worlds together. At the last dinner she noted that the son made a bunch of “you made me do this” type statements to his father regarding things from the past like: “remember when you made us move” (they were still married then, and it was actually the other spouse who wanted to move), “remember that horrible course you made me take”, “remember that trip where you made us ride the stupid boat and I flipped out.” She said he was not hostile to her, but never asked her a single thing both times, only answered her questions politely. To the point of why she came here upset, apparently after dinner the son flipped out with his father, she was not there, and was upset that his father had “a life he knows nothing about.” I have been divorced, but never had a situation like this, so I don’t want to misadvise. To me it seems like some control issues on the part of the son. She’s here looking to me for advice and comfort. I am hoping someone here might have some wisdom to share, thanks very much.