baseclly, Shun liked Mio then Mio left and promised to communicate with him when he called not he answered but Eri and she told him not to confuse Shun and let him think about it deeply, after three years when Mio decided completely and became an adult he came back and told him he loves him, Shun refused-he wanted Mio to live a normal life because he loves him too, and it's because when he had to get married he said at the wedding he loved boys and the family did not accept it, when they were together(shun and mio) the ex-fiancé wanted Shun to come back because his dad was sick, Mio wanted him to go because he knows it's hard to lose a family (both his parents have passed away) Sean wants Mio to come with him and he agree,
Happy ending ╮(￣▽￣)╭
Basically*
I didn't understand a thing that happened