The Investment Model of Commitment: Why People Stay (and Why They Leave)

Satisfaction, alternatives, and investment — the three levers of lasting commitment

What determines commitment in a relationship and how can you strengthen it?

Caryl Rusbult’s Investment Model proposes that commitment is driven by three factors: satisfaction (how good the relationship feels), quality of alternatives (how appealing life outside the relationship seems), and investment size (what you’ve put into it that would be lost on leaving). All three are modifiable — and understanding which is weakest gives a precise target for strengthening commitment. The model has extensive empirical support across diverse relationship types and cultures.

Most people think about relationship commitment as a feeling. Rusbult’s Investment Model reframes it as the output of three inputs — how good the relationship is, how good the alternatives look, and how much is already invested. This reframe is practically powerful: it tells you exactly what to work on when commitment is eroding, and it explains why satisfied people sometimes leave (high alternatives) and why dissatisfied people sometimes stay (high investment). Below are practices derived from each model component.

Practices

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