We have joint accounts, but I handle all the bills and it's really hard as he likes to use the debit card for everything, every night and that's attached to the checking. Plus, his pay sucks when there's no overtime-2 weeks take-home is one mortgage payment. My part-time money barely covers gas for the month. Most of the bills are either past due or close to being so, but I don't say anything since there isn't much we can do about it.
If I want something extra, I stash cash in a box for a few weeks-that I'm pretty good at! For us, seperate accounts simpley would not work-he's worse at paying bills than I am-I like to pay more than what's due-he used to pay minimums. I still have to remind him to write his ATM usages in-we've been short quite often because a withdrawal wasn't entered.
Your SO needs to set priorities-hard to do when young as you don't see the longterm consequences til it's too late. Our retirement plan now? work til we drop dead