I Ignored My Dry Girlfriend for Too Long and She Turned Into a Yandere

The protagonist, Nagamine Seiji, has a girlfriend, Oishi Karen, whom he has been dating for three months. Concerned about what others might think, the two had kept their relationship a secret from those around them, but one day, Karen’s attitude suddenly changed. Seiji repeatedly asked her out on dates, but she prioritized her plans with friends, leaving him feeling as if he were being rejected even though they were dating. Then one day, Seiji witnessed something—Karen was on a cozy date with another man. Consumed by sadness, Seiji made a decision—he would let the relationship fade away naturally. He found it painful to initiate the breakup himself, but he also didn’t want to be the one to be dumped. He concluded that the best course of action was to let the relationship fade away naturally, so he decided to ignore Hanae from now on. However, things didn’t go as Seiji had planned…?