פירוש על קידושין 96:1

The Talmud now rejects the idea that this debate is over betrothal with a loan. The issue here is whether we consider wages to incur incrementally while the work is performed or only at the end. The sages would say that they incur incrementally, from beginning to end. At the end of his work, she owes him money and he forgives the debt. This is not a valid form of kiddushin. R. Meir would say that the debt is incurred only at the end, when he actually performs the betrothal. There is no loan here, only him converting the money she now owes him into betrothal. Since there was never a loan, this is not betrothal by loan.