I know that the cost/benefit dynamic in a relationship, which some calls giving/receiving dynamics, is not a new concept. So, I am not surprised to find papers that describe in mathematical terms a relation and the underlying second law of marry-dynamics (http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0009881 open access)
What I am interested to talk about are the perturbation to this simple optimization. As such, a perturbation will bring far from the optimal conditions. How far, it depends from the magnitude of the perturbation. Is this sufficient to reach a new optimal state (maybe, a divorce)? It depends on the surrounding of the initial optimal conditions. Resistance to perturbation, in a real system, ensure that the relationship remains solid. I think we can classify the resistance under two categories:
Tolerance allows to resist perturbation, by extending the surrounding of the initial optimal conditions. Say, your partner become violent. You can buffer the violence to some extent, then you give up and move to another state of relationship
Expectation means that, even if the perturbation is very ample and potentially destructive, you resist as you know that this state of things is only temporary.
In both cases, the resistance to perturbation requires a limit, otherwise the person enduring the perturbation (assuming that the other is causing it) will eventually destroy the partner.
The resistance to perturbation is therefore a very human act, an attempt to solve problems, a (less positive) will to maintain a status quo. It is important to perceive and define the limit, and also the motivation that bring us to move the limit away from our safety, in a dangerous zone of abuse and violence.
the gain for a better understanding of the limit and its motivations is immense: you got your life back and recover full use of your brain.