my only suggestion is that the MC should start to go through some fundamental psychological changes, after having gotten a dick, because futas are actually more aggressive than males. she should have to try to fight off the urge to mate every female within a very short period of time, since it's the norm for them to go that route. and she should notice that all females start to become more aggressively enamored with her, because of her pheromones that she begins to emit in a wide field around her, which causes them to be triggered into mating mode....
best examples of this are on "the terrible fairy"'s videos, check them out (best example is "the to do list")