Because they deserve love too. And there's no place for them in bl relationship except as friends or family. As much as his wife is strong and willing to be a part of her husband's life and accept his behaviour, i can't help but feel sorry for her. I hope she also finds herself a lover soon and someone who will trully love her and her alone.
Scarlet Beriko always have cool female characters, they all have their own stories and are not just like part of the background
Sorry to say, but in the manga that follows the story of Yakitora's son, she is dead.
Why arent there more characters in bl like Ane san? Bl women majority of the times are depicted as spoilt annoying brats, who try to 'change' a guy to being straight, or kiss him focrcefully even when knowing he like someone else.