A decision to divert is generally a rare occurance but when required is done with safety in mind. I don't know the specifics of this flight but various factors are considered. BDA often has strong crosswinds that near limitations for a particular aircraft type. That combined with thunderstorm location and movement are factors. Norfolk is the nearest alternate for Bermuda and sometimes a decision is made early to divert to be at the head of the line to the alternate, because if necessary, all the other aircraft would be going there as well. In the 30 minutes later that the other aircraft landed the dynamics of the local weather could have changed. A revised weather forcast after departure is not uncommon. I would suggest our ontime performance is near the top in the industry. That combined with our designation in the past as the world's safest airline should ease your relatives' concerns.