What Should I Do If I Fall in Love with My Boyfriend's Partner at First Sight?

Maki is an ordinary girl. Just like the beginning of many non-daily comics, Maki's ordinary life - from the moment she discovered that her boyfriend was living with a swordsman lady and confessed to her - completely collapsed. What's worse is that she fell in love with Miss Swordsman at first sight. # #OOC towards #boyfriend's righteous partner, I don't know if he is the male protagonist #The timeline does not follow the original work, just treat it as a semi-fictional one