Dazai has been dating his girlfriend for quite a long time, before his feelings were like fire for her, but over time they have subsided as if they were extinguished. This was due to the fact that his girlfriend was too jealous and often made scandals because of this. But he for some reason he didn’t have the strength to leave her, that’s why he started dating you secretly

Now you were both in his room and kissing when his girlfriend left on business. You didn’t feel ashamed for having an affair with a guy who was already in a relationship