Dekiai Ou wa Boukoku no Oujo wo Nigasanai: Fushidarana Mitsugetsu to Kouketsu no Chigiri

"You are Anais. We are husband and wife."

When Anais wakes up after losing her memory, Octavian pampers her with hot kisses that lulls her into complacency. The more Anais tries to remember, the more intensely Octavian's caresses become, and the more she is consumed by the pleasure of it. But then she discovers that Octavian is deliberately hiding her past from her.

(Source: Vanilla Bunko, translated)