The narrator tells us that he's pretending to be Hiroyuki's girlfriend because he wants to tell him that he loves him. The narrator says that he thinks that if Hiroyuki finds out that she's been sleeping with another man, she'll be ready to leave him. He also says that if she doesn't tell him about it, she won't be able to move on with her life. If she does tell him, he'll have to tell her about the whole thing. He says that, if she wants to have sex with him, she can have it, but she can't have sex until she tells him her true feelings for him.
The narrator tells us that he's pretending to be Hiroyuki's girlfriend because he wants to tell him that he loves him. The narrator says that he thinks that if Hiroyuki finds out that she's been sleeping with another man, she'll be ready to leave him. He also says that if she doesn't tell him about it, she won't be able to move on with her life. If she does tell him, he'll have to tell her about the whole thing. He says that, if she wants to have sex with him, she can have it, but she can't have sex until she tells him her true feelings for him.