What does the author mean by this sentence?

I remembered that girl inexplicably. I used to hate the world so much, but because of her, I fell in love with it. Suddenly I feel that everyone in this world is very cute, and everything in this world is very fun and interesting.

Simply put, this sentence means that I like that girl's mood, and it can also be understood as "because of you, I fell in love with this world".

So the meaning of this sentence is not "meet one, love one, play one" or "it doesn't matter who you love, it doesn't matter anything". But since a sentence has been written and spread, everyone who sees it can have their own understanding.