"Realistically, when people are thrust into horrible circumstances they learn to cope very quickly or they don't survive."
That line just gave me a mod idea. Probably not an easy one though.
You see, more than anything, it's the "don't survive" part that RW needs to be able to simulate.
It should be pretty obvious - a system that can simulate mental breaks is only good for anything if those breaks actually do happen from time to time.
Besides, situations change. Even from the outset. People crash-landing is one thing, local tribe is another and five gazillions of user-generated scenarios are downright not possible to account for by the same reaction levels.
Solution – dynamic reactions, based on “shock levels” and “adaptation levels” (think “expectations”, but more detailed and developed) on top of the static system.

Now, about your examples. (keep in mind I'm not saying vanilla numbers are exactly right, I'm just saying why I think the gaps DO have place where they are)

1 Cheating is generally taken as a personal betrayal. You guys seem like one of those “welded together” couples, so maybe you don't get it, but love can be a REAL ♥♥♥♥♥ when it goes south. It's a natural coping mechanism. Being infatuated with people who treat you like dirt is absolutely not healthy.
By contrast I assume that selling someone to slavery is a colony-wide decision. Your personal feeling weren't treaded upon in the process. And you don't have a specific target for your hatred. No one chose someone else over you, no one lied to you, no one broke your heart and so on and so forth.
Vanilla's contrast is a bit too much IMHO, but a huge chunk of it should be left there.

2 The other thing you lovebirds don't get. Not every couple is actually meant for each other (most are not, in fact) and people are relative creatures. Marriage happens at the peak of marriage for many people, and for most it's at least close to the peak. Death can happen by the time you're sick of each other and your poorly matched union. Hell, if anything, the oversight was that there's is a guaranteed -25 for a dead wife in vanilla.
But then again, we'd need a deeper system than vanilla with time-based and relationship-based reactions to simulate this properly, so for a simplified system -25 is alright.

3 Ever heard about egoism? Now, I'm not gonna fall into the same trap that the western culture did and say that it's somehow natural to be a self centered freak, but it IS what the world's dominant culture keeps telling people not so subtly.

4 And this is where your own angle starts to backfire. Remember the whole adaptation and crisis spiel you gave us? Yeah, people wanting to see more blood and murder are the morons who never had any in their lives. If you even took a good look at our civilization you'd know. People are least ♥♥♥♥♥♥ AFTER the war and most ♥♥♥♥♥♥ during the times of peace and prosperity. We grow insensitive to death (all kinds of suffering actually) when we are so far removed from it. THAT is how people came to take it lightly and see it as entertainment. RW colonists, on the other hand, know it closely.

5 Obviously, I agree with you on this one.
And I also agree with the reasoning in the parts that came afterwards.