no, inheritance is not marital unless you commingle it with marital funds
I could not find anything that precluded an annulment after separation
here is some basic information
Dissolution of Marriage (Divorce):
A dissolution of marriage, which is more commonly known as divorce, terminates the marriage of the spouses and resolves issues between them, including child custody, visitation, child support, spousal support, asset and debt division, former name restoration, and even restraining orders.
Dissolution of Domestic Partnership:
Domestic partners are "two adults who have chosen to share one another's lives in an intimate and committed relationship of mutual caring." Persons of opposite sexes may not constitute a domestic partnership unless one or both of the persons are over the age of 62.
A legal separation case is similar to a dissolution of marriage or dissolution of a domestic partnership in terms of the range of issues that are resolved in the case, except that the parties remain married or registered to each other.
A nullity case is more commonly known as an annulment of marriage or an annulment of the domestic partnership. This can only be requested based on one of reasons listed below.
Grounds for Termination of Marriage
For dissolution of marriage or legal separation in California, there are only two legal grounds. The first is irreconcilable differences, meaning the marriage or partnership cannot be saved. The other reason is incurable insanity which, unlike irreconcilable differences, must be proven.
If you are seeking a nullity of marriage or nullity of partnership, you will need to prove in a court hearing that your marriage satisfies one of the grounds listed below. These must have applied at the time you and your spouse married or you and your partner registered:
incest means the spouses or registered partner are close blood relatives.
bigamy means a spouse or partner was knowingly married or registered to another person at the time of marriage or at the time of registration of domestic partnership.
underage means a spouse or partner was below age 18 years at the time of marriage or registration of domestic partnership and did not obtain parental consent or a court order permitting the marriage.
Prior Existing Marriage or Prior Existing Domestic Partnership:
prior existing marriage or prior existing domestic partnership means a spouse married or a partner registered on the mistaken belief that his or her previous marriage or partnership had ended in the death of the other spouse or partner, who in fact was still living.
unsound mind means a spouse or partner could not and has not formed the intent to marry or registered due to a mental condition.
fraud means deception regarding a significant matter that led to the marriage or the partnership and continued until the breakup.
force means threats or acts of harm were used to force one spouse or partner into the marriage or domestic partnership.
incapacity means a spouse or partner was and continues to be physically unable to consummate the marriage or partnership.