Set the precedent now. At some point you setup a joint account for the shared expenses and keep your own bank account for your own stuff. My money, my stuff.
I mean it, I'm VERY happily married and this is what we do (I'm not saying it's what makes us happily married... but it does make ME happily married, LOL). I told her before we got married that I spent 25 adult years trying to get my shit together and now that I have I'm not about to have to ask someone if I can buy something. NOT GOING TO ASK PERMISSION AS A GROWN ASS MAN. PERIOD. END OF SENTENCE.
PS: I realize you didn't say "ask for permission..." but wanted to help you out since you're not yet married.