That's why
With this I can only assume you artificially increased her points, which with this games, breaks it beyond repair. at this stage she should only be around 65 points not 300.
As I keep saying to everyone, Do Not artificially increase relationship points unless you're following the walkthrough and know how far you need to go before moving onto the next section.
The only thing you can do now, it start a new game. and keep you hand of the cheat section the hallway, unless you use the walkthrough and then only do it as the walkthrough tells you.