So is Pacino's lover a woman who wants to turn into a man or a man who wants to turn into a woman? Asking because depending on which transformation it is reflects the polarity of Pacino's sexuality.
Transsexuals (even preoperative ones) usually choose bisexual or straight men since gay men would not be attracted to a man who grew breasts, nor one who had his penis chopped off and replaced with a vagina.
In real life, the Pacino character (John) left his wife and kids and had become immersed in the emerging gay community, where he met and fell in love with the Sarandon character (Ernest/Elizabeth). John proclaimed himself gay (but he was the type who probably would've had sex with a farm animal if given the opportunity) and was against Ernest getting a sex change, but Ernest had his heart set on it -- and John had his heart set on Ernest. In the documentary "The Dog," there's an '80s interview with the two in which Elizabeth states that the sex change was used to sensationalize the story -- John's actual motive for the robbery was because he was in debt to the mob. Unfortunately, John refused to elaborate on the accusation, as did the makers of the documentary.
Actually, John and others who knew him said that was a lie about him owing the mob money. In the film 'The Dog' it was said people came to that conclusion because John is Italian and the mob owned most of the gay bars in New York City, but there was no truth to those rumors.