My Girlfriend Cheated on Me With a Senior, so I’m Cheating on Her With His Girlfriend is a Manga/Manhwa/Manhua in english language, Comedy series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

Yuu Isshiki, a first year university student, learns that his girlfriend Karen is having an affair with his senior, Kamokura. He was so shocked and devastated that he asks Kamokura’s girlfriend and the most beautiful girl on the campus, Touko: “Please have an affair with me!” A thrilling romantic comedy that begins with an accomplice relationship. This series is slated to release on the 27th of January 2022!