At the moment it happens only in "Route C" of his... route. To get it you need to pick "Deny it" on Day 21, "Agree with him for now." on Day 22 or/and "I need to be quiet" on Day 24. After that "Be firm" and "Keep pushing" on Day 26.
That why i said or/and. To get locked out of "Route A" and get the "Route C" you need to mess up atleast 1 of 3 choices. "Tell the truth / Deny it" on Day 21 is one of said choices. I was able to get Route C even by messing up just the first choice.
