I'm a Daughter that's Timid to the MAX, but I Still Agreed to a Bet with my Tactful Fiancée

I'm a Daughter that's Timid to the MAX, but I still Agreed to a Bet With my Tactful Fiancée is Reincarnation isekai manga.

A geology university student in Japan ends up murdered by pure bad luck due to walking into a convenience store that's being robbed at knife point. If that wasn't bad enough, just prior she learned her supposed boyfriend was only using her; plagiarizing her geology studies for himself and his real girlfriend.

She awakens in the Otome Game Caroline and the Rainbow Magic Sweets that she played in her past life, as Pia Rockwell; the unseen and unnamed fiancee of one of the capture targets, Rufus Stan. Disguising her past life memory as a prophetic dream, Pia gets Rufus to agree to a contract to help set her up as a geologist and look at for the heroine in the future; though his clause is that she would wed him immediately upon Caroline failing to seduce him.

Trivia

 * Pia never expected or planned for the marriage wirh Rufus to go through; expecting to have him break the engagement at minimum.
 * What Pia didn't count on was Rufus falling in love with her because of her purity; having shown she had no interest in wealth and status, but only wanted to be loved.
 * In a very humorous moment, Pia completely ruins the romance between her and Rufus when he says he wants her "most precious thing"; she hands over a shark tooth fossil, having missed Rufus was implying sex.
 * The Stan family has "ninjas" under their command for protecting them and their loved ones.
 * They are one of many dark secrets about the Stan family. But Rufus and his father plan to keep Pia ignorant of the truly dark things they deal with; not wanting her purity to fade.
 * Due to her geology mapping skills, Pia accidentally made herself a target for enemies; due to them mistakenly believing that the Stan family had hired a strategist.
 * Rufus mentioned that this issue would die down once birds eye maps were made commonplace.
 * Rufus tested Caroline's rainbow cookies on lab rats after she gave him a batch; finding out they have an addiction effect on the eater the more prolonged the ingestion. This causes humans to confuse the addiction with affection for the one who made the sweets.
 * Caroline is a reincarnation as well and attempting to live vicariously through the game moments. However, things are off when she appears.
 * She is acknowledged as an illegitimate chold a year earlier than on the otome game by her father.
 * She gives the sweets to capture target Henry Cox, whom was already in a loving relationship with Pia's best friend Erin White; causing Henry to become delusional about Erin, and making the poor girl retreat to her family home to deal with her pain.
 * Caroline is taken aback when Rufus tells her that he loves his fiancee dearly and has no problems with her; contrasting the strained arranged marriage she knows from the game.
 * She further digs her grave by mentioning Rufus helping his father after the latter was recovering from poison; something that was not public knowledge.
 * Caroline appears to be genuinely after the prince, as the opening scene has him annul his engagement and later attend the opera woth Caroline when she joins the story.
 * Pia ends up earning a PhD for her fossil knowledge; getting to be a professor before even starting high school.
 * Rufus mentioned that serves as a measure of protection against Caroline attempting to get her banished; since a professor is highly respected and valued.