The financial analysis of major life decisions tends to be conducted either too emotionally or too narrowly. The status quo has costs. This is an observation so obvious it should not need to be made, and yet it routinely escapes the financial analysis of major decisions.
The woman considering leaving a marriage thinks about what divorce will cost. She often thinks less carefully about what staying is costing: the emotional toll, the opportunity cost of the years, the effect on her health.
The most useful framework is a full-cost accounting: what does each option actually cost, including the hidden and non-financial costs, and what does each option actually offer?
The most expensive decision a woman can make is often the one that looks, on paper, like no decision at all — staying because the costs of leaving are visible and the costs of staying are not.
The practical tool is simple: write down what it is actually costing you to stay and what it would cost to change. The comparison is rarely as stark as the fear suggests.