This is the sequel to Eien Shika Hoshikunai. The asshole ex is one of the mc here. Tbh, if I didn't read the other story, I would've never expected him to be an asshole. He's portrayed so beautifully and kindly here. The uke is a poor thing tho. The story completely revolves around them two and doesn't have any external stigma. You can enjoy this manga as a standalone but not as a sequel. Pretend lovers to actual lovers arc.
Dekiai Keiyaku