Yuusha Tsuma Yuusha ga Shitekurenakute mo, Seijo wa Kedamono Maou ni, Musabora Retemasu

Saint Iris finds herself deprived of "sex" by her husband, the former hero Yuri, sealed behind a locked chastity belt. Living a life devoid of intimacy, she encounters a fierce-looking demonic man. His name is Magres, the new lord who now rules the demon realm…! Thus begins an immoral love fantasy between the sexually aggressive demon lord, the neglected saint, and the emotionally abusive hero!

(Source: Yanmaga, translated)