The 2nd scene is the flashback with Arisu. To unlock it you ned to choose "Reminisce" after her dialogue. The 3rd is the threesome with Alex and Emily, you need to be on both of their paths.
The android version does not have persistent saves, hence the existence of the chapter select screen upon starting a new game. I know it's not an elegant solution, but idk much about Android porting and that is the best I can do. :(