Why would the bail people tell me it wouldn’t be worth writing a bond for my fiance?

We are focused on the sentence, "the bail people said it wouldn't be worth it". Depending on the conditions for the bail as set by the magistrate at the arraignment, the bail bondsman's reply sounds like they are weighing their risk. The bonding company must guarantee the court that your fiance will appear for all court dates. If the amount is too high, or the court thinks the offender is a flight risk, either they feel he might flee or they know something (not disclosed in the question) and will not even take your money.