In some cases, after a marriage ends in Illinois one former spouse starts paying spousal support to the other. An alimony order does not always have a set end date, but that does not mean the payments will last forever.
Under Illinois law, one reason to terminate an alimony order is that the ex receiving the alimony gets remarried. Of course, many people are reluctant to give up their spousal support, even if they fall in love again. So instead of getting married, they try to have the best of both worlds by moving in with their partner. They live as spouses without formally marrying.