I was also eaten by that man today (real-life version) White Flower Warmth MIMK-140

Aisaka Haruna, a bright and talented student with a boyfriend and beautiful appearance, is living a perfect life. However, her relationship with her boyfriend is a laughing stock in the school, which is tacitly accepted, and she is torn between her feelings and those of the lowest-ranking teacher. Unable to resist, she loses her virginity, but hides it from her boyfriend, suffering from deep guilt. Ultimately, Haruna and her boyfriend get married, but what suddenly flashes through her mind is the sexual pleasure she experienced with that lowest-ranking and most despicable teacher…