Rikon Sunzen!? Kamen Fuufu Kara no Dekiai Seikatsu: Kowamote Gunjin wa Oku-sama ni Muchuu desu

Leila, a down-on-her-luck noblewoman, gets a helping hand from her first love, Silvester, a wealthy soldier, by entering into a contract marriage. They have been a couple for three years now, without having even having consummated the marriage. Leila expects her husband to divorce her at any time, but he is attacked by an assailant and loses his memory of their arrangement due to his injuries.

"My wife is so beautiful,” he says, "It makes me want you so much.”

Having lost his memory, Silvester begins to dote on Leila with sweet, seductive words.

(Source: Sankosha, translated)