Perhaps Beom was a bit childish lol. However I guess if you think about all three of them (Dowon, his brother, and Taeju) have history. So Beom is left out. So if you didn't tell him, Beom would just be clueless. And perhaps say something that would put them in an awkward situation. Anyways, it was funny and now that it's out he doesn't have to hide this from his brother and taeju won't feel like a hes some hidden taboo anymore.
Perhaps Beom was a bit childish lol. However I guess if you think about all three of them (Dowon, his brother, and Taeju) have history. So Beom is left out. So if you didn't tell him, Beom would just be clueless. And perhaps say something that would put them in an awkward situation. Anyways, it was funny and now that it's out he doesn't have to hide this from his brother and taeju won't feel like a hes some hidden taboo anymore.