You know how every mobile phone in the past used to be unique and quirky and nowadays all are just rectangular plastic bricks, yea... Thats happening with smart watches now I guess
In Persona 3, as in other games in the series, you can only romance certain characters. You cannot romance every character in the game. You'll have to choose which character you want to pursue a romantic relationship with, and depending on the choices you make throughout the game, you'll have opportunities to deepen your bond with that character.
Only if you play the Portable Version of Persona 3 and Play as the Female Protagonist! (Shinjiro, Akihiko, Ken and Ryoji) Otherwise and in this Game: NO!
In "Persona 3 Reload," which is a re-release or remake of the original Persona 3 game, there are indeed male characters with whom the protagonist can form strong bonds and friendships, but there are no options for romantic relationships with male characters in the traditional sense.