Doutei Joshi Shinsatsu-shitsu, Okuchi no Ishi wa Shojo Danshi Bangai-hen

Eiko, the daughter of a respected dentist, was set up in an arranged marriage with Shuichi, a brilliant dentist, for the sake of her family! Eiko immediately tried conceive a baby with Shuichi even without love, but for some reason, Shuichi refused to have sex with her! Little by little, he kept touching her in all her sensitive places... until her mind and body are getting all confused...!! This is a spinoff of "Okuchi no Ishi wa Shojo Danshi", about the relationship between Sakura's parents.

(Source: Shueisha, translated)