Norman being attracted to Marion wasn’t the only reason for her death
I’ve been rewatching Psycho again and noticed that the only reason for Marion dying that was ever discussed, is that “mother’s” jealousy was triggered by Norman being attracted to Marion.
The psychologist mentioned he got to know everything from “mother” and then goes into his explanation that focuses exclusively on the attraction/ jealousy of Norman/mother.
But after rewatching the scene of Norman and Marion conversing, I don’t think it’s that simple.
Marion asks him personal questions, and Norman gives her these helpless answers. He seems to feel uncomfortable having to acknowledge how pathetic his life is, which might make “mother” fear he could leave her. Marion makes a comment about not tolerating someone talking to her like his mother talks to him and his expression falters for a moment before continuing benignly defending his choices. He even tells Marion how sometimes he would like to leave.
And from knowing that Norman and “mother” engage in conversations, we know “she” is present throughout all of it.
I can feel the tension building subtly.
So as soon as Marion suggests to send Norman’s mother to a lunatic asylum, the switch we see being flipped in Norman, doesn’t come out of nowhere. It build up over the course of this conversation.
And I personally think it’s not just Norman talking anymore as soon as he leans forward and starts to dominate the conversation.
It’s a version of Norman we never see again after this scene (except while telling Arbogast to leave). He’s confident and imposing, like a third personality next to “mother” and “submissive/nervous Norman”. It seems like he’s in complete symbiosis of being Norman and mother at the same time.
“Mother/Norman” must feel like this girl is trying to separate them from each other. He’s angry at Marion, and after snapping back into his shy persona, he seems less reverent of Marion but not less sexually effected by her.
After she leaves, and telling him her real name, he checks the name she checked in as. So he knows she’s lying about her identity. In his (mother’s) eyes that probably “tarnishes” his opinion of Marion.
So I think it’s not just the sexual attraction and Norman spying on Marion that triggered “mother” to act, but it was more a last straw situation for “her” to take over.