Hello David! I really like the idea of being able to choose the gender of the Love Interest! However, the rules would not allow you to have 2 different sprites.
So what I would suggest you do is to draw an androgynous Love Interest and allow the player to:
- Choose their pronouns
- Choose the Love Interest’s pronouns
This way you could even accommodate for many genders: man, woman, non-binary, etc…
If you are using Ren’Py I’d thoroughly recommend npckc’s Pronoun Tool.