Basically what you should do is just choose options that focus on 1 girl. If there are no options for the girl you're focusing on, then you can choose whatever you want. The game loops endlessly, so all the content is open to you for when you eventually get around to it. If you're unsure on whether or not you've seen all the scenes, you can check the gallery at the beginning of every loop and during calibration that happens on every day.
Also, Alexa has Dom/Sub route, so when you go through her stuff, just choose all of one in a loop and then the other in another loop. Same thing for lesbian and futa options.