I liked the story but I agree it was so annoying when he kept mentioning the ex, also i found it kinda weird how his brother was dating his ex...
Shino was actually his brother's girlfriend from the very beginning. She cheated on his brother with Seryou as a revenge ( because seryou's brother cheated on her first) because she knew he also had feelings for her.
So basically shino never liked seryou she just got with him for revenge, and then broke up with him to get together again with his brother... but he still liked her while being with yuzuru but eventually developed feeling for yuzuru and now they're a couple
Yeah. He liked her all this time but knew that she liked his brother so he stayed away from her and tried dating however he didn't fall for anyone and kept breaking up untill he met Yuzuru.. but as he said he no longer had feelings for Shino even during the beginning of their dating week.. he just couldn't ignore her because he knew she was miserable because of ber brother.. just like he himself was because of her. Shino however, in her moments of weakness always went to Seryou as she knew his feelings for her and kinda used them to feel loved because she couldn't forgive and get back with his brother despite loving him. (Hope it helps ╥﹏╥)
tbh I'm disappointed, probably because I didn't read this manga years ago like other commenters here...but I really didn't like the seme（￣へ￣）
this story had a lot of potential, and I was very much into it until the seme mentioned his ex girlfriend, after that the whole story just went downhill all the way until the end...