Kanojo no Oshi ga Kirai

The troubles of the handsome college student, Kei Tachibana, is that his cute, older girlfriend, Chisa, is crazy about other men. What's more is that the men are 2D "Oshi Characters." What tomorrow will Kei-kun face as he fights against those blasted "Oshi?" This is a love comedy between a younger, devoted boy and working otaku girl!

(Source: Shueisha, translated)