Book idea I've thought a lot about

Male and female fall in love, it's like a Romeo and Juliet kind of love, male commits a crime and is sentenced to life in prison. Female cooks up a plan to be with her lover forever. She starts with getting a sex change becoming a male. She commits a crime, is sentenced to life in prison. Her new home is with her lover in prison. They live happily ever after as A gay couple. Together, same cell. Just think of every step and what has to be done, the hurdles and people involved, the things that can't be controlled and ones that can. And everything in-between! I've thought of this as modern day and as the times of kings and queens.