shirotsuki's Favorite

Please help me find this yaoi manga! It's about a rich (famous?) author who lived alone in his mansion and one day finds a guy injured outside the gates. The injured guy claims to be being chased by some bad guys so the author allows him to stay. The injured guy is actually an undercover detective/private investigator hired by the husband of a female friend(?) of the author because he suspects an affair. The author falls in love with him, but when the detective is exposed he confesses that he was there to investigate him and then leaves him.