AITA because i asked my friend to "assume" the rent while i am out of town

So, long story short, I am heading out of town for about 3 weeks and I live in an apartment with a friend and we pay the rent 50/50 each month. But since i am going to be gone for 3 weeks straight, it will be the better part of a month that I am not going to be there. so i asked him if he would be cool paying most of the rent that month because, well, he is basically going to have the place to himself for 3 weeks. I even did the math already for him and I showed him what to pay. He went ballistic and said he wasn't going to pay that. I thought he would understand because, well, its basically going to be his apartment for 3 weeks and not mine. wtf do i do? i will be showing him what the comments say so, I would appreciate it if you all took my side as fellow redditors.