Fear of Commitment in "Psycho".

While watching the opening scene the other day something became quite obvious to me: Sam Loomis (John Gavin) perhaps doesn't want to be with Marion Crane (Janet Leigh).
As they share a post coital conversation (with sex so good that she didn't even have time to eat as Hitch suggests by showing us a wrapped sandwich) he tells her all the reasons why they can't be together.
Most of them concerning money and his ex-wife. Marion rolls on the bed like a kitten as she confesses she can't be without him and is tired of the secretive life they're leading.
As she gets dressed, and he remains shirtless, the idea that she might break up with him becomes tangible (while they're naked she's still his'?) and he says "I want to see you under any circumstances, even respectability".
Anyone who's seen the film knows that he never will see her again, which led me to question if in fact everything that happens to Marion afterwards isn't in fact a manifestation of Sam's fear of commitment with her.
She steals the money because of him and it's this event that gets her killed (that the money becomes irrelevant to the plot perhaps suggests that this wasn't going to solve their life as a couple as he said).
In the opening scene Marion also mentions that ideally she'd like Sam to eat with her in her family house with her mother's portrait on the mantel.
By specifying the mantel she seems to be putting her mom into a sort of immovable pedestal.
And what scares off a heterosexual male more than meeting his girlfriend's mother or his own in any case? Maybe he isn't as scared of her mom as to the idea of what his own mom would think of the way he's leading his life and the thought of disappointing her.
This piece of dialogue is a sort of premonition of what will happen to Marion later on. She is, technically, killed by someone's mother.
It's as if Sam's fantasy of guilt reversal is realized.
This all might be dismissed by the fact that when Marion disappears Sam helps in the investigation. But this might as well be one part guilt, one part need to fulfill his role in the equation and embrace responsibility (is he making sure she won't come back to have his way with her sister or any other woman?).
Or maybe, just maybe, Sam really did love Marion Crane.