Boku no Ai wa Fushidara ni Yugan de Iru

Living together with her boyfriend for the first time. Yui always gets dumped because of her caring motherly personality, but she hopes that this time she'll finally be able to live happily ever after, but she soon finds out that her boyfriend is cheating on her. With nowhere to go, she ends up staying in the room of her close childhood friend, Mizuki. They've been together since they were little, and she thought she knew everything about him. But then Mizuki says something meaningful to her in a low tone: "Don't ever come into my room"...? A thrilling, sweet, and strange obsessive love that crosses the line between childhood friends!! (Source: Bunkasha, translated)