I don't like the fact that you can break up J and L. It's meant to be a romance crime story, not "partners-in-crime" crime story! (long rant)
So the news came out today that you will actually be able to break Jason and Lucia, and that they would stay simple partners-in-crime. And also that it doesn't affect the story in any way. The romantic elements of the game are completely optional and outside of dialogue and maybe some additional mini-games, it probably doesn't have any weight within the story. Likewise the ending won't feature their potential break-up or marriage or anything related to their mutual feelings. You're basically playing as two roommates with added-on option to romance. You might say I'm exaggerating but that's wha