If you're looking for manga similar to Watashi to Kare no Omiai Jijou (Light Novel), you might like these titles.
Chihiro is an OL who's not good at remembering names. Suddenly she was forced to change departments and was in a pinch! Even if she could remember names, everyone is indistinguishable because of their suits! Meanwhile, a male employee always gives her her favorite pudding. Chihiro nicknamed him Pudding Tanaka, and they became close friends. Throughout that, he was always a gentleman, but something changed...