Brangwen seems to have had few sexual partners; she isn't telling herself of numerous people that desired her and just figuring that the problem lies solely with Cloud.

True, she is pretty inexperienced. She has had sex for fun, but not often and not with anyone who means anything to her.

You have her hands and her lips moving, but I wasn't sure if that was Elena's or Brangwen's hands or lips.

Mostly it was Brangwen. Elena was pretty passive until Brangwen told her she was allowed to touch her back.