Help my friend find this manga's title

There's 4 main character: 3 of them is friend together in which 2 of 3 is a couple and the other one is crushed by younger brother of 1 out of the couple. Idk what I'm saying because this is my friend trying to describe this me but it's definitely a manga and it's yaoi. Pls help my friend cus they were trying to find it for weeks now.