C l u m's Favorite

This is like third or fourth time im trying to find this manga but i always found it on my own but everytime i forget what it was and now i seriously just cant remember BUT IF SOMEONE HAS READED IT: it was like this young guy and older dude and older one is looking for his long lost (adoptive?) Brother cuz their parents broke up and then he meets a guy and sex etcetc what usually happends BUT HE FOUNDS OUT THE GUY HE SLEPT WITH IS HIS LONG LOST BROTHER and then they broke up and thats all i remember also tho in the end they fight cuz younger guys "new" Brother is mad that The older "Brother" is inlove with his BROTHER so they fight cuz lol im sure this was very clear explanation xdddd