I'm thinking of splitting bills with my gf even though I earn way more than her
Why do you think you should split bills even though you earn more than her?
I think it's the fair thing to do.
It's your money and you're free to use however you see fit. Even if you earn way more than your gf it's ok if you want to split bills with your gf.
That's right, I shouldn't be expected to pay all the time.
True, it's important to set boundaries when it comes to spending money as that's an important part of a relationship. I think if you talk to her about it she'll understand.