Belle only started liking Beast once he started actually trying to be nice.

No, and imo this goes for OUAT's Belle too. There are a ton of other issues I have with that ship, but Stockholm Syndrome is not one of them and it kinda irks me that other anti-Rumbellers toss it around so lightly.

^^ Yeah. She even decided to break the rules and just leave because she couldn't stand him at first.

She hates the rude Beast until started to leave him. She started to like Beast after he became a better one.

She left the castle because she understood her moral boundaries. She couldn't keep a promise to a person like Beast and only fell in love when he changed.

I hate it when people say this. Belle didn't fall in love with the Beast until he started to change and become a better person, and she even left the castle twice - once before she fell in love with him, but once after - because, like @anukriti2409 said, she understood her moral boundaries. Definitely not Stockholm Syndrome.

Maybe? You could read the story that way, but I always felt the movie tried it's best to portray her independence. She doesn't really allow for others to decide for her, and even breaks promises just to get her way. She's a prisoner, yes, but she stands her ground against Beasts tantrums.

This again? It's getting old.

She only started warming up to Beast after he saved her from the wolves.