Divorce or death and remarriage have the same legal result. If you don’t set up a Trust (or Will) that states who you want to get your property, the person you are married to will get up to ½ of all Separate Property and all the community property. The community property will include everything mixed together (and most people combine their assets).
Understandably if you divorce or die, you don’t want the new wife (or husband) to get everything you built during the marriage; you want your kids to inherit the property you and your former spouse had during your marriage.
Trusts can be set up during your marriage to protect your assets so that when your spouse remarries, they can’t leave everything to their new spouse. If you are remarried after a death or divorce, you can set aside assets for your children from your prior marriage. No one should count on the word of their new spouse that they will do the “right thing” and after your death leave the assets they inherit from you to your children. Most people will end up leaving it to their children or even their family.
Remember, when you divorce, you must update your estate plan! You should update it when your spouse dies and always when you remarry.