Boyfriend [33M] earns 75% more than me [24F] but insists on 50/50 rent split. What’s the fairest way to approach this?

I had to reduce my hours to part-time at my job due to my chronic illness, and i’m making considerably less than when I was FT. However my boyfriend still thinks we should split rent 50/50.

On paper, I make $1,259 per fortnight after tax and he makes $2,200 p/f after tax, sometimes a $100-$200 more. Roughly 75% more than me. Our rent is $1,590 per fortnight, our agreement right now is it’s 63% of my income and 36% of his. I’m finding that even when I budget strictly i’m running out of money after rent and groceries and end up having to rely on his at the end of the week if any emergencies come up, which is causing us stress.

I did the math and if we agreed to split proportional to income, i’d be paying 45% of my income for rent which is $572 p/f and he’d be paying 46% at $1,018 p/f. He’d still have quite a lot left over.

I’m happy to go 50/50 on all other bills, but I think this is fairer that way i’d struggle less paying for groceries and emergencies. I’d appreciate hearing your guys’ thoughts on this.

TL;DR: I [24F] earn 75% less than my boyfriend [33M], but he insists on a 50/50 rent split. I want to split by income. What’s fair?