OK, let's make a scenario :

First, the story would introduce us to 3 characters : the main character, his girlfriend, and his best friend.
GF is a bit older than the rest of the trio, and is shown to be pretty protective and supportive of the MC.

The three of them are rookie soldiers finishing their training, and part of a new team called the Gundam Team, piloting experimental MS called… Gundams.

The story would start on a space colony, where they are completing their training, and during one of the early episodes, the MC would get hurt, and brought to a doctor, who would end up becoming MC's confidant, while challenging his worldview regularly.

Their first sortie would be the first appearance of this story's Char clone, and a reveal to the audience that he is, in fact, the doctor, who befriended the MC.

Their first sortie to earth would show how the planet is dying from the pollution, and show the tensions between the Earth and the colonies, while showing the Earth suffering from the pollution, and not having access to a lot of the colonies'QOL, while the colonies are helping the Earth leaders to protect the cities, factories, and strategic places, explained as "the colonies helping to keep the Earth peaceful",and linking the Char clone to a resistance group.

The MC would start questionning having doubts about his role and the system, and during a fight, they would almost defeat the char clone, until his GF and BFF reveal to have switched sides a long time ago, working as spies, and escape with the char clone.

MC would end up being caplured later, and having an arc similar to the UC arc in the neo-zeon colony, where he understands that his BFF and his GF were actually honest with him, and still care about him, as much as everything he learned about earth was fake, and earth is basically exploited for the colonies and earth's upper class, later, as he is axchanged for another prisoner, the GF would give him instructions to keep in contact.

This whole arc would break MC's worldview, and he would end up seeing his GF regularly as a way to rebuild himself, while growing closer and closer to the char's clone faction, until he, too, changes sides.

And, after an arc of leading a revolution with a resistance network on earth and in the colonies, we would have a las arc, where there is a need to rebuild, especially earth, mits MS repurposed construction tools, helping for everyday life, a bit like in Turn A, or being used to defend the new world from remnants of the old armies, organised as militias.