Can't Help Gettin' Hurt:

Shouji thinks his boyfriend's first love, Terumi, might still have feelings for Honami, so he goes to investigate. He discovers that Terumi is happily married. Now, it's Shouji who can't get Terumi out of his head. Things become more complicated when Honami's lingering feelings for Terumi surface. Cult author Mika Sadahiro is known for her style of angst-infused and sex-driven plots.