I love these kind of cutout games, though I have some suggestions.
* There should be a gallery mode, even if it is for the only girl currently present in the game.
* Winning the final level of a girl shouldn't bring the player back to the main menu immediately, you should wait for player's input to do that (advancing to the next level should also wait for the player's input).
* The game over screen has an exit button that does nothing, it should either do something or be removed (in unity you can make this button only visible in certain builds).
* The game over screen should have a way to go straight back into a new game with the same girl, rather than forcing you to have to go to the main menu.
* There should be a way to quick reset AND to exit from within a level, either through a button press or through the pause menu.
* You should consider resetting the players lives back to 3 between levels. 3 lives with no health pickups for 5 levels is very old fashioned and feels hostile. If you want a difficult game, you should consider increasing it elsewhere.