Thank you so much for playing and sharing Grace's Diary!
One of the great things about these video games is that they are a safe way of experiencing an otherwise dangerous situation. Please do not feel guilty about what happened in the game! As you suggested might be the case, you experienced just one of the possible endings in the game - there are a total of three endings (one of which is considered the 'good' ending).
Now that you've experienced one of the 'bad' endings you have more information about what does - and sometimes doesn't - work when talking to a peer about dating abuse. (Having more examples of instances where Grace witnessed unhealthy behavior would have helped Grace keep Natalie on the phone.) This game experience was obviously meaningful to you - and having impactful experiences by playing games like this makes it less likely that those people will ignore a situation like this if they see it IRL.
We strongly believe that video games are the best way to explore, share, and discuss these difficult and sensitive topics.
Thank you again for your kind comments and interest in this game. Feel free to check out our other games as well --- all of them are free, several are available for iOS/Android --- and although all are related to the mission of our charity (prevention of teen dating violence) they include different themes like consent and gaslighting. Since 2008 we've produced more than 50 short, but impactful, games!
HINT: if you decide to play again remember that some items should be looked at more than once ;-)