Lovey-Dovey Newlywed Life of the Strongest Hero and the Cute, Expressionless Assassin

Eld, the strongest hero who once defeated the Demon King, and his partner and lover, Chloe, the world's strongest assassin, have completed their final mission and decided to retire and begin a peaceful married life. However, their affectionate interactions are somewhat awkward, as they know nothing but battle...!? An otherworldly romantic comedy begins, featuring two innocent yet powerful individuals!

https://www.cmoa.jp/title/309981