"The Expert at Unrequited Love Wants to Support His Childhood Friend Who Was Cuckolded"

My childhood friend, for some reason, always gets his girlfriends stolen from him. I had harbored feelings for him since I became aware of things. Since I wasn't seen as a girl, I ended up giving him love advice, but that day he made an odd request of me. "Mutsuki! Please go out with me! When I'm with you, I want to understand why I feel the urge to cheat. Please teach me when that urge comes up! I can only ask you! Please! I'm begging you!" A contract relationship between him and me. Thus began my days investigating why he felt the urge to cheat whenever he was in a relationship with me.