The manga is about these 3 guys who fell for the same girl, who loved them all back equally but passed away. The guys somehow ended up having sex with each other as a way of getting over their bitterness and grief, but one of them was hinted to actually having feelings for another. For a little more detail, I vaguely remember one of the guys being particular mean to one of them and pushed his anger onto him, while the other guy tried to protect him.

Please reply if you have any idea!! I've been searching quite desperately for it. Thank you so much in advance!

maybe Koi no Kawaki?

Yes! Omg thank you so much <3