@aFFi the new girl is probably a screenwriter, will see the will they won't they, hear their loud rejections at being a couple, and do the logical "I am a master of human dialogue" thing, that all writers fall into at some point, screw with them until they clarify their relationship status. She will probably realize she's in love with MC just as he makes things official with FMC, just like all the romcom clichés tend to do.