As a number of posters have said, this is extremely petty, unpleasant, childish behaviour. I would not be marrying this man. He. Will. Not. Change.
I used to be with somebody, and actually lived with him for a couple of years. We were together for four years all together some years ago. He earned probably a third more than me at the time, but he insisted we paid 50% for absolutely everything. Bills, rent, food, household items, furniture etc... everything. If we went out for a meal, and it was, say, £28.00, and he'd had £13.50 worth and I'd had £14.50 worth, he would make me pay the stupid amount extra. He would only pay £13.50 and would make me pay MY £14.50. He wasn't paying any of the extra £1.00 that I spent.
In the pub he would get himself a drink, and get the money off me to get mine, or just make me go to the bar myself. One time we went to see a show at the theatre, and the tickets were £10.00 each. He got the tickets, and he wouldn't give me my ticket until I gave him the £10.00.
He made me pay exactly half of all the bills and the rent. And even when I had to have time off for six weeks after I've been in hospital and had surgery, and I was only on sick pay, I still have to give him half towards everything. I was left with nothing and had to dip into some savings (which wasn't much of to be honest, probably about £500.)
I was very young. I thought this was the way things were. Quite a few men I have known in the past had kept the money to themselves and gives the wives 'housekeeping,' and it was always a very low amount. But I was flipping working. I just wasn't earning as much as him.
The straw that broke the camel's back was one particular incident where he had caught me taking a fiver from his wallet because I couldn't find my purse anywhere. He screamed in my face that I was a thieving cunt, and smashed up my little stereo, and said 'I DARE you to steal the money from me to replace THAT!'
I moved everything of mine out of our flat, and moved back in with my parents while he was at work one day.
Sounds like an extreme comparison to the petty scales thing you have, but the thing is, my ex STARTED like this... BE WARNED.
@HogwartsForever11 Please leave him. You will have nothing but a life of misery with this man. Thing is, whilst some may say it's only fair you pay the same if you're sharing anything, and it's not HIS fault you are not as high an earner as him, the thing is, he will be like this when you have children with him, and are not working - or are working part time, and not earning as much. He will never change, he will always be petty and spiteful and financially abusive, and keep HIS stuff to himself.
Me and my DH share everything, including finances, so most stuff is not his or mine, it's ours. Only with personal stuff do we have our own - towels, toothbrushes, hairbrushes, roll on deodorant etc...