Well, there not really a "secret" but when you get your boutique on style savvy you unlock dominics mansion, and the buyers center. Later on, you unlock the contest hall when Rococco comes to your store for the first time. then you unlock the hair salon and cosmetic store when Olivia, and Didi arrive in your store. And No unfourtuatly, you do not date dominic, but after you get your thousanth costumer he takes you out to a "fancy" dinner. he also gives you the fairy princess set.
Thanks and Peace. xD