Unsentimental Relationship Models

I've been thinking for a week now - trying to find the right inspiration as to the pros and cons of the unsentimental relationship models ABCDE and Social Exchange Theory.
To start with the ABCDE model, I take issue with the fact that it is taking a critical-theoretical stance on a subject which is so blatantly situational-interpretive. On a macro level I don't believe that this model is really that helpful. It's not news to anyone that relationships build, continue, and end. It does give us a foot to start on as we ask the 'why and how' questions about any of the 5 steps.
How do relationships start?
Why do relationships end?
What spurs the deterioration of a relationship?

Why does one let an abusive relationship continue?


Any information that can come from this model will all be a product of individual circumstances. I suppose that if one were to learn that 'financial disagreements' were a proprietary source of relationship doom, then that person might take steps in their own life to maintain a healthy flow of economic dialogue between himself and his partner in an effort to not be a part of that statistic, but this just takes us full circle back to the idea that each relationship is individual and cannot be summed up by a model that's as simple as ABC (DE).

I'm more accepting of Social Exchange Theory because it's life in a nutshell. I might argue that everything we do can be summarized by a cost/benefit model. From crying for another serving of breast milk to ultimately deciding to leave my wife for that perky little waitress who served me last night (I would never do that!).
Ah yes, Social Exchange Theory may look cold on the surface, but it's just another day in the life. Some people have different ideas about how costly a cost is and how beneficial a benefit is. This is why we so often hear the phrase "I can't believe those two are still together" or "I would never date you but I have a friend who I really think you'd like."
Even the healthiest relationships fit into the SET, it's just that the costs don't seem like costs. You might even say that you have a flourishing bank account of love. Aww!

Here are some situational interpretive outlooks on relationships:

The Perfect Breakup

Cost/Benefit Analysis

I chose these videos to illustrate how every single relationship has its own unique story behind its successes and failures alike. Where the models discussed do not provide any insight as to why a relationship is at a given stage, the characters featured here could hardly be more clear about how ending a relationship is not always such a negative thing, and also provides good specific insights as to why the benefits are sometimes not worth the cost.