The unreliable narrator of My Cousin Rachel

A friend asked me about My Cousin Rachel—whether it’s atmospheric like Rebecca. I think I’d say no, the 2 novels are quite different. Rebecca is essentially about Manderley, and Rebecca’s presence in the house—her belongings, her style, her influence, her popularity among the employees. There are actions in Rebecca, especially in the later half, but a large part of the novel is in the narrator’s mind, as she obsesses over Rebecca, imagines people’s gossip about her and criticisms of her, or over-analyses her own awkwardness and inadequacy. 
My Cousin Rachel is also told from the 1st-person’s point of view and has a naïve, inexperienced narrator, but it is less internal. Daphne du Maurier also has the difficult task of writing Rachel—writing Rachel from Philip’s perspective, and so far I think she does very well. The reader can see why Philip likes Rachel, despite having believed her to be responsible for Ambrose’s condition and death. 
The guy is naïve and doesn’t have very good self-awareness. Sometimes he behaves like a child. 

“… I threw a lump of coal upon the fire, hoping the clatter bothered her. 
“I don’t know what’s come over you,” she said; “you are losing your sense of humour.” And she patted me on the shoulder and went upstairs. That was the infuriating thing about a woman. Always the last word. Leaving one to grapple with ill-temper, and she herself serene. A woman, it seemed, was never in the wrong. Or if she was, she twisted the fault to her advantage, making it seem otherwise. She would fling these pin-pricks in the air, these hints of moonlight strolls with my godfather, or some other expedition, a visit to Lostwithiel market, and ask me in all seriousness whether she should wear the new bonnet that had come by parcel post from London — the veil had a wider mesh and did not shroud her, and my godfather had told her it became her well. And when I fell to sulking, saying I did not care whether she concealed her features with a mask, her mood soared to serenity yet higher — the conversation was at dinner on the Monday — and while I sat frowning she carried on her talk with Seecombe, making me seem more sulky than I was.” (Ch.14) 

This is very telling: 

“Then in the library afterwards, with no observer present, she would relent; the serenity was with her still, but a kind of tenderness came too. […] I wondered, watching her hands with the silks, smoothing them and touching them, why it could not have been thus in the first place; why first the pin-prick, the barb of irritation to disturb the atmosphere, giving herself the trouble to make it calm again? It was as if my change of mood afforded her delight, but why it should do so I had no remote idea. I only knew that when she teased me I disliked it, and it hurt. And when she was tender I was happy and at peace.” (ibid.) 

It is obvious to readers, though not to Philip, that Rachel’s been playing him. She knows exactly how to control him, how to get the right information (e.g. find out his feelings about Louise and other women) or how to get him worked up, how to get him to do what she wants without realising it (e.g. she mentions teaching Italian to get him to sort out money for her, then acts angry when he does), and so on and so forth.  
At the same time, Rachel is very likeable, and the fact that she plays Philip and twists him around her fingers doesn’t necessarily mean that she’s manipulative, in a scheming, dangerous way, or guilty of Ambrose’s death. We have to see.  
It’s interesting, though, to see him become weaker and weaker, more deeply in love with Rachel, and less rational. 
See his reaction when he comes across an unfinished letter from Ambrose, stuck in a book: 

“I was swept by a kind of shame. What business was it of mine to probe back into that past, to wonder about a letter that had never reached me? It was not my affair. I wished to heaven I had not come upon it.” (Ch.15) 

His infatuation with Rachel becomes more important than his love for Ambrose and desire to find out the truth. He has forgotten about the final letters, he wants to forget this one. 
In fact, if we go back a bit, to the scene of Rachel and Philip opening the boxes and sorting out Ambrose’s belongings, I can’t help noting that even though there is some sadness, Philip’s more occupied with Rachel: 

“I kept moving my lips against her hair. It was a strange feeling. And she was very small, standing there against me.” (Ch.14)   

And: 

“I hoped she had not noticed — I had barely noticed it myself — that for the first time I had not called her cousin, but Rachel. I don’t know how it happened. I think it must have been because standing there, with my arms about her, she had been so much smaller than myself.” (ibid.) 

I know the point people often make is that Philip, in his inexperience, becomes easy prey for Rachel and loses all reason, but I can’t help finding it odd, the way he reacts to sorting out Ambrose’s possessions. I have faced loss myself, when my grandma passed away, I remember how I felt when going through her things and deciding what to do with them. Philip talks of his love for Ambrose, but I don’t quite see it. Not in this scene. Not in the scenes when he’s back from Italy either (see my previous blog post). 
He seems to move on very quickly, Rachel gets all of his attention. 
What does this mean? I do not know. But it’s interesting.