Splitting rent

My bf makes around 5.5K a month, and I make somewhere between 3.9-4k a month. He has a lot more bills and loans to pay than i do. At first we agreed, that he would pay a little more… like he pays 55%, I pay 45%. now out of nowhere he wants to do even 50/50. the rent is A LOT and im barely gonna have money to save or use personally. I feel weird fighting to pay less. I don’t wanna be a brat but i think paying proportionality to what we make and so we can save an even amount was perfect. what do you guys think I should do?