To reach 80 with Danielle
you need to have done the following
I followed the walkthrough losely. I met her in the park a few times and ended up with an uneven score (45 or so). Then did the beach even in the spoiler. It takes me to 75 no problem, but then does not give me points until 80, contrary to the walkthrough.
That also means she kicks me out of her house when asked to show tits.
I just cheated the 5 points and everything was fine, but it was frustrating for a while because I thought I missed an event.
Edit: I wanted to make a savegame at the exact point for you guys to replicate the issue. I found that while my first part of the statement is true (beach event goes to 75, not 80), I just got unlucky and she shows tits at some point, meaning you can progress. I know I tried at least 4 times before and got kicked out every time, so I assumed it was impossible.