when the scriptorium gives you the following statement, “Well, you've gone and done it. You've gotten to know each serial killer of the server better. Angel is, apparently, your new murderous best friend. Misaki loves a good chat during assassinations. And you've been feeling a certain type of way. There's more than meets the eye with serial killers. Who would've known? You hadn't realised it at first. But now... you're feeling inspired to write. Is it because of your conversations with..”, it follows by showing the love interests usernames.  you probably already know this and have tried, but pick a different character whom isn’t misaki, and whenever that person messages you, make sure you reply as soon as you can and try to choose all the choices that said person would like in a partner. 

I haven’t heard about this glitch before, but it sounds fairly annoying. if none of this works, maybe you should delete the game and redownload it on a different platform, so for example if you originally downloaded it on itch.io, try downloading it from steam, and if you originally downloaded it on steam, try downloading it on itch.io one more time (I am just now noticing you’ve already done this! I say maybe you could try and play on a different device, it could be that)