If both parties agree to keep their own retirement, is there an Ohio law that says after 15 years of marriage, you MUST split them equal or is it whatever the two of us decide among each other?
You can work out whatever agreement on property division that works for the both of you. A judge will review it for obvious imbalance.
If the one retirement package is worth more than the other you should be prepared to explain why the division is fair (i.e. the one with the lesser retirement is getting the record collection to make up for it).