The Banished Villainess' Husband

The Banished Villainess' Husband is a unique isekai reincarnation manga. Rather than be told from the perspective of the reincarnator, it is instead seen from the perspective of the titular spouse.

Eufram D'italie is unknowingly a character in story. His "friend" prince Alephado decides to lie that his fiancee Elana Ruthfett Forsythe has been bullying the girl blessed by their nation's guardian dragon, Rifana; in order to get Elana banished and the Rifana engaged to him in her place. Making matters more complicated is that Eufram is hitched to Elana next and has to leave the country too.

They move to the neighboring country, where Eufram has his distant relatives set up a home for them. Surprisingly, Elana is elated to be gone and is enjoying her new life. She takes charge of his inventions and makes business deals with the local merchant. Eufram spends his time making devices Elana asks for, eventually learning she had a past life and rhe current world is a novel she read before.

Trivia

 * The reason Alephado's plan worked is everyone will stupidly believe at face value if someone blessed by the dragon is being hurt in some way; since the dragon could rampage if it's chosen one is harmed.
 * Elana explained she's broken the novel series story thanks to her memory coming back when the prince framed her. She was originally supposed to seek out a cult to summon an evil dragon and get killed by the prince. However, she doesn't want to waste her second life over an idiot prince and head full of flowers heroine
 * Each nation has a guardian dragon of another color. However, they each have a different prejudice against others for their hair color. Elana's green hair is liked in her new home, while everyone insults Eufram for his red hair; even his uncle calls him a ba****rd nonchalantly.