God's injustice towards Adam and Eve

[Tonus]

As noted, we're not given their thoughts, and as you agreed such thoughts could reasonably explain their actions.

Also note that the creation of the entire universe is covered in about a page. These accounts are not intended to be exhaustive. We're left, probably intentionally, to contemplate these things.

Right, and that's what I'm doing. Wondering what is missing that would make the story reasonable. I am left with the unsatisfying but nonetheless realistic possibility that either or both of them simply made illogical or irrational decisions, but even that is a bit of a minefield, which I think is made a bit worse by Paul's input.

Did you ever consider that Adam, not being deceived, was taking an intentional stance with Eve out of love for her and/or fear of being alone?

Yes, I considered that. Without Paul's input we could at least consider the possibility that the serpent's case was compelling enough to deceive them both, but Paul removes that possibility, so another option is what you propose. The problem with having Adam choose Eve over god is that shortly thereafter, when god is questioning them, Adam doesn't hesitate to throw Eve under the bus.

No, they still had time to consider the situation and change their understanding of it.

But their fate was sealed once they took the action.

First, fear of god is the beginning of wisdom.

I know that text, but I find the implications of it to be a bit troubling.

Second, if you focused on an episode in any relationship in which someone is found to have done wrong, it may seem as though fear were the total of the relationship.

But that's only part of the equation here. For starters, Eve seems nonplussed at the fact that a snake talks to her, and appears to have no issue taking its word over god's. The serpent doesn't do anything particularly clever, he just tells her that god has lied to them and withheld something of apparent value (although even that is questionable-- of what value is freedom in a paradise where the only apparent rules are to make babies and avoid one tree?). Eve accepts this without question and turns her back on god without much thought. We don't know Adam's reaction or thought process aside from the claim that he wasn't deceived, and therefore knew that he was choosing against god.

Children may fear a parent, but they can also feel love and admiration for them, and loyalty to them. If fear is the primary motivator for our relationships with those close to us, it strikes me as a bad relationship. Adam and Eve don't appear to have that moment where they wonder what god with think of their actions, or how god will feel, or what he might say. That detachment would seem odd for a human child who has a healthy relationship with his human parent. For a human "child" who presumably has a healthy relationship with his god, it's a detail that sticks out like a sore thumb.