Honestly I find these a little insincere to what we blatantly see in the actual film. There's no need for a 'struggle' between Rey and the dark side, because in that final sequence she's drawing her entire power from the dark side. She becomes incredibly aggressive, she is clearly angry, and she has just suffered the death of 'the father she never had' and the presumed death of one of her friends. Rey had no struggle there, because she has absolutely no reason to let him live. The camera changes as Ren is knocked onto the ground to follow Rey, and slows ever so slightly, to signify the dramatic moment where she is just going to flat out murder him there while he's knocked on the ground defenceless. In contrast to the idea that she doesn't even get a second to contemplate whether to kill him, I very much think the truth is closer to her never even considering to spare him. Yes, the novelisation resolves in a different manner, and she's compassionate and a clear source of light in the film, sure, but in the film every strike she makes in that final fight after she begins to listen to the force is aggressive and reminiscent of Luke in Return of the Jedi, and she's stopped only by the separation (which is contrived in how cleanly they're brought about, that I can definitely agree). I honestly vehemently disagree that Rey having a struggle between the light and dark isn't introduced in that final fight as filmed.