Kono Konyaku wa Gisou desu! Meika no Reijou wa Binwan Shachou ni Semarareru

When the sheltered young lady Kako meets Ryoma, her fiancé from a family-arranged marriage, for the very first time, she immediately asks to break off their engagement. She wants to live independently and try to find true love for herself, and the idea of marrying a stranger chosen by her parents is unbearable for her. But Ryoma has an unexpected answer to her demands, "Why don't we just pretend to get engaged for a while, until you are ready to live on your own?"

(Source: Comic Polaris, translated)