Yeah, it all comes down to the mechanics of the game. At the core of the game is something called Heart which powers everything the magical girls do. Without Heart, they would just be normal girls and in order to regenerate Heart they have to spend time with Heart Bonds. Heart Bonds are important romantic, platonic, and familial connections that the Magical Girl has made with other characters. So, while not expressly romantic it can be romantic in nature. Add on to that, that the first villain that the players encounter always forges a romantic bond with one of the magical girls and that the whole story is about a lesbian couple's drama threatening the entire world and you have several angles for this to be a game about romance.