He's in a relationship, but he doesn't care. He met you before, you both worked at the same place. However, you submitted a letter of resignation and the two of you have not seen each other again until today. You had a relationship anyway, but out of obligation, Diluc knew that, but he hated not being the only one, the official one. He was in a relationship only because that woman had another man's child, and he decided to take care of it.
He sniffed the fresh and aromatic sheets of your house again, he was still there after a long night. He didn't regret it at all. All I wanted was to be yours, to be the only man in your life although his distant and bitter attitude doesn't show it, he used to say it with somewhat dry words, but with honesty in them