itch.io

You can always utilize the save scuming  if youre really struggling that bad^^ although in my opinion most of the dialogue options are pretty straight forward. Some girls have more difficult branching stories than others . 

Harems are "doable" but requires you to plan ahead and in most cases having high kink and somewhat balanced sexual preference of targeted harem (50 or 60% lesbian cant remember but it tells you exactly in the ingame walkthrough)  is what you need before having sex with more than one girl from that harem without locking yourself out. 

You need to finish Cassidy story to progress with the office harem and there is a way to make her submissive. 
If you cant be bothered with completing office harem on your current playthrough you can simply tell her to F. off when she ask you to give her a lift to airport and you wont see her again  ☺️ 

Theres always NG+ so you can focus even on one girl at a time and keep your skills from books so you dont have to grind again.

Tried sex slave cassidy? or girlfriend cassidy?

I dont remember having problems with emma when Cassidy's status was that of sex slave.

"You either play it with wiki open or you're in for a hard time."

this is and has always been my biggest complaint with this game
Emma is my go to example for this considering her path can get closed off you are not careful on sams path