It could also be done as a skill that turns you female, maybe have an area where only females are allowed and men are instantly jumped and milked dry, maybe some kind of monstergirl/amazoness village(not sure it´d fit the game), so that to get through it you´d have to turn female. They wouldn´t have grapples for your female form (possible a few exeptions, but redoing animations for all girls would be too much work), but maybe give the female MC a smaller seperate healthpool, that when depleted turns MC back to male, or health remains the same pool for both versions, with limited skills in female form, and turning male again when reduced to zero.
Just airing ideas I got from reading this