Why is it a bride-elect?

I never voted for any of these women. Why not “future bride” or “[future groom]'s fiancee”?

Because elect comes from eligere meaning to choose. The groom chose the bride, he elected her.

Why is what ‘bride-elect’? Is that like bride-to-be?

The hard part was winning the primaries, I think.

Found this on the topic.

Seems like it’s just an old term than got ingrained by its traditional use on wedding-related invitations.

Haven’t there been several notable instances where an elected person’s spouse carried on in his stead while a replacement was found? Senators & such? or is that just the work of fiction?

You may be thinking of the first three women to be elected as governors, each of whom was married to a previous governor. I was in CT when Ella Grasso was elected governor, and much was made of the fact that she was the first female governor elected “in her own right.” I imagine something similar might have happened with other positions, but these are the cases that come to mind.

Jean Carnahan was appointed to fill her deceased husband’s Senate seat (a seat that he was actually elected to posthumously) until a special election was held a year later.

The first woman to be elected a U.S. senator had first been appointed to her late husband’s seat: Hattie Caraway - Wikipedia

Why is appointing the late politician’s widow to fill his seat, even a thing? No disrespect intended, but I hardly think being married to a senator qualifies someone to be a senator. I wouldn’t expect a car mechanic’s wife, or a doctor’s husband, to be able to serve in their stead. (Bad analogy, I know.)

The spouse of a senator or representative is expected to vote the same way as the recently departed. After all, most of what a senator does officially is cast votes. At the same time the public will sympathize with the appointed spouse which avoids the controversy that would surround anyone else.

It’s called widow’s succession and originally the idea was that she was only a placeholder keeping the seat warm for the party. Then alot of these widows started developing political careers in their own rights.

Nicely reversed in The West Wing where it’s a man who succeeds to his wife’s seat.

Obviously, someone was a fan of the Mikado.

The work that a politician does personally is just the tip of the iceberg in doing the politician’s job. The rest is done by the politician’s staff. Most staffs are like a large official household, all well known to each other and to the politician’s family. A deceased politician’s spouse is most likely to know and trust the existing staff and, more to the point, to keep them on and let them keep doing their jobs without trying to change too much. alphaboi867 is right that the spouse keeps the seat warm for the party, but the spouse minimizes disruption and turnover in other ways too.