I recommend I Am a Fiendish Cultivator. The male lead, Mo Wentian, is a Fiendish Cultivator, while the female lead, Qiu Yu, is not. In the story, Mo Wentian roamed the immortal cultivation world, not being bound by the secular world. Qiu Yu was an important character in his growth process. She was Mo Wentian's heart and faith. I hope you like this fairy's recommendation. Muah ~😗