Hmm, I’m not really sure about the personalities of your characters so this situation may not work:
MC’s friend invites her to this party. MC goes and her friend introduces her to LI and LI’s friend. LI’s friend says something rude or sexist which MC shuts down and then walks away. Then either LI or LI’s assistant hands MC a business card and reveals they want her to model one of their products (or whatever he sells).