Don’t assume that a business you owned prior to marriage remains entirely a non-marital asset after marriage. If your business or professional practice increases in value throughout the marriage due in part to your spouse’s contributions, your spouse may be entitled to a share of the increase in value upon divorce or your death. Such contributions can be obvious, such as in bookkeeping or entertaining clients. But they can also be more subtle, such as in taking care of the home and children so that you can focus on running the business.

source: findlaw.com