Are there any practical alternatives to signing a prenuptial agreement?
Possibly, but they may not hold up in legal terms. That’s why if you want to protect your rights and assets, you should connect with an attorney with an expertise in family law.
As an alternative to a legally-binding prenuptial agreement, each party should prepare a complete list of all their own property (e.g., inventory your assets) and finances (e.g. bank accounts, investment accounts, pensions, brokerage accounts)—as well as the debts each owe—well before the wedding day. Share the information with one another and have the inventory signed by each of you.
Then, at the very least, keep your own property acquired before your marriage separate and don’t commingle it with the marital property or the other’s property. Preserve its separateness by keeping it in your own name. When you sell or liquidate any of it, deposit the proceeds in a separate account in your own name and do not deposit any marital funds into that account or use that account for the benefit of the marriage. If you decide to use some of your funds for a common purpose and invest, the money will have changed from separate to marital property.
This may not protect your property from the other, but it will make it clear what you started with that was yours.