Illustrative example
A payor learns that the former spouse receiving maintenance has lived with a partner for three years, shares the bills with him, and introduces him as her husband at work events.
Cohabitation alone does not satisfy the text however long it has run or however tangled the finances: the section requires habitual living with another person and holding out as that person's spouse, and even with both established the court may annul the support provisions rather than must. So the case rests on the holding-out element, which is about how the couple present themselves rather than how they split the rent.
Maintenance steps down over twelve months to nothing, which spares both of them an argument about what holding out means in front of anyone else.