The gemara asks; How do we assess the amount the false witnesses have to pay based on how much they tried to make the husband lose? Which means, how do we assess the avantage the husband has in regards to the kesubah based on the fact he is currently married to the women, compared to the amount he would have to pay if he were to divorce her? There are two ways a husband can gain monetarily because his wife is currently married to him which will therefore minimize his loss. The first way is he can sell the land designated to the women in the kesubah, that he would eventually give her, to someone who will profit in a case where the woman dies first (In this case the husband will at least gain some monetary value from the property that will eventually go the women or the man who bought it, instead of him having to give it to all to her without first benefiting from it). The second way is he can buy the wife’s potential benefit she will get if she is widowed or divorced, which was written in the kesubah. In this case the woman will sell it for less than what is actually written in the kesubah, to the husband, and he will not have to pay her the money in a case where she is widowed or divorced (he will buy it for less now to not have to pay more later and is therefore minimizing his losses now, and that it what the false witnesses are trying to take away from him). In the second case, where he buys his wife's rights to the kesubah he would gain more than if he wanted to sell his land in order to minimize his losses. How so? If the kesubah was 100 maneh and the husband wanted to sell his potential benefit of selling the land, the buyer would give him 50 maneh. In this case the husband would benefit 50 maneh from the fact the woman is still married to him. In the first case the wife would sell her rights to the kesubah for 40 maneh and the husband’s benefit would be 60 maneh (the husband is paying X amount now to not have to pay 100 maneh later and his gain is the 100 he won’t have to pay latter minus the X amount he has to pay now). The reason he two potential values are different is because the wifes potential value is not worth as much to the buyer as the husbands potential value for two reasons, one in the case of the husband selling his land the buyer will automatically acquire the land in the event the women dies, while in the case he is buying the kesubah from the women he will need to go to court and collect the amount owed to her in the kesubah which is annoying, and this would cause the buyer to pay less; the other reason is in the case of selling the land the buyer will be able to benefit from the land by continually eating the produce of the land (until the wife is widowed or divorced, which would cause him to have to give it back), while there is no benit to having the wife’s kesubah in the meantime. This would cause the husband to be able to sell his potential benefit for 50 maneh, while the woman would only be able to sell it for 40 maneh. This would make it clear that the husband can buy the wife’s entire kesubah of 100 maneh for only 40 maneh, and the benefit of his wife being married to him is 60 maneh as explained before. The gemara asks how we assess this case. One way is looking at it based on someone buying the the wife’s potential benefit (if she would be divorced or widowed and got the money designated to her in the kesubah), which is 40 maneh causing the false witnesses to have to pay the rest, which is 60 maneh. They have to pay this because they made him lose the remaining 60 maneh by the false testimony that he divorced her because they were trying to make him pay the entire amount of the kesubah at 100 maneh. The language of the mishnah implies this because it says “we calculate how much a person would pay for the woman’s kesubah based on the chances she gets widowed or divorced.” Based on this it seems we base the amount on the wife's side. On the other hand it would not be correct to calculate it based on the women’s right to the kesubah and take the entire amount minus the potential value of selling it as explained before. This is because the husband might not have lost that amount of money through the false testimony because she might not have agreed to sell her right to the kesubah in the first place. This means we should not assess it in this way, and instead assess the amount based on how much a buyer would be willing to give the husband for the potential benefit of the kesubah land if the husband would want to sell it. This is 50 maneh in the example above which is the same amount the false witnesses would have to pay because that is what they tried to make him lose. When the mishna states “we assess how much a third party would be willing to pay for a women’s kesubah based on the chances if she is widowed or divorced,” it does not mean the wife's rights to the kesubah, but rather how much a person would pay the husband for the land designated in this kesubah whose status is in limbo because if the woman is widowed or divorced she will collect the land, but if she dies the husband will get the land permanently, thus the mishna means the court assess the amount based on the husbands potential benefit (50 maneh) and that is what the false witnesses have to pay (it is what they tried to make the husband lose).