Ketubot 108 - One who puts his money on the horns of a deer
A husband who goes oversees still has an obligation to provide for his wife. As we learned before , his possessions may even be sold for this purpose.
Imagine that someone else, the husband's benefactor, decided to provide for the wife's upkeep. Even though he thus saves the husband from potential losses, still, when the husband returns, he has no obligation to repay his benefactor. In general, if one pays up his fellow's debt, that fellow does not have to repay for this - this is the opinion of Chanan, one of the two judges whom we met before .
Other Sages (who, incidentally, were sons of High Priests) disagree and require the husband to reimburse the benefactor. Rabbi Yochanan ben Zakkai concurs with Chanan and expresses it thus: "The benefactor is like one who puts his money on the horns of a deer" (where he is likely to never see it again).
Art: Deer In A Landscape by Johannes Christian Deiker