Maximising rewards and minimising costs are important but SET fails to take into accounts the need most people have for equity in a relationship.

In this theory equity = fairness

What matters most with equity is that both the partners level of 'profit' are roughly the same (rewards - costs)

Has the potential to cause distress - happens when 1 person gives a great deal and gets little in return, same for those who receive a lot and give little in return.

Over benefitting and under benefitting = both inequity, under benefitting partner feels greatest satisfaction in form of anger, hostility & resentment.

The over benefitting person will likely feel guilt, shame and discomfort, thus satisfaction is about percieved fairness

It's not the size or amount of the rewards and costs that matter - it's the ratio of the two to each other.

Problems arise when one partner puts in a great amount of effort and gets little from it. A partner who is a subject of inequality will become distressed and dissatisfied with the relationship of it continues that way.