“When her domineering boyfriend forces her to join the army the Potomac with him, a meek farmgirl fights for the North and for her relationship as she succeeds in battle just as his cowardice grows.”

There's definitely something in all this. As dpg said, the true story of a woman being unmasked by her pregnancy is great.

I think there's something incredibly romantic about the women joining to be with their husbands and the audience wouldn't struggle to get behind her if she signed up under her own volition. If he's forcing her though, the romance dies straight away. His motivation for joining can stay the same and he can turn into a bully when his cowardice (and her prowess) starts showing. As she gets promoted, he almost reveals her true identity to a group of her soldiers resulting in an epic "I am Spartacus" moment where all the soldiers express their loyalty regardless of her gender (even though it's never confirmed at this moment). This way her desire to save the relationship (and therefore enlist) is totally understandable and more importantly she's never been forced to do anything. Her merry band of soldiers then becomes her family in a way that the boyfriend (why not husband?) never was and she realises that she wasn't as happy as she thought she was. The boyfriend then becomes the antagonist. It's a classic Fool Triumphant (Undercover Fool) film with the boyfriend becoming the "Insider". Final act is her fighting and winning on the battlefield but she gets mortally wounded and is at death's door. Her disguise slips and her commanding officer (who represents the establishment and strictly anti-women in war), despite the truth being revealed orders her soldiers to carry "his" body to the med-tent. She ends up dying as a medal is pinned on her. We then discover that the whole story is being told to her child who was raised by her tent-mate with the help of the rest of her band of soldiers.

After enlisting incognito to fight by her husband's side during the Civil War, a meek farmgirl discovers her true calling as she's promoted through the ranks while her cowardly husband flounders and threatens to unmask her.

Lacks a clear goal but I really like the idea of a Fool Triumphant based on real life.

I hope you find a story in all this. I would watch it!