Friend from across the hall from her fiancé, who is about to get married, cuckolds her without her fiancé’s knowledge – Natsu Igarashi

"This is my fiancé..." One day, Natsu, a childhood friend who I've loved since high school, came back to my parents' house with his fiancée. The childhood friend I looked through the window every day in high school will soon be someone else's...I can't...