Regarding estimates

In the SD
In the yeshiva where I study, we are currently dealing with a question concerning rape in a condition related to a divorce. The question appears in Tractate Ketubot, page 2b. The question is related to a similar issue in Tractate Nedarim, as I think on page 27a. There the Mishnah deals with a modar in order for him to come to eat and rape occurs. When the modar arrives, he is exempt from the rape issue. The Rabbi and other rishonim explain the ruling that it is because he did not know that he made a vow, that is, an estimate. Can it be said that such an estimate is a kind of additional condition that was not stated, that if an uncommon rape occurs, the condition will be canceled, and the cancellation of the condition is in total the fulfillment of the aforementioned unstated condition?