Annulment laws exist to provide couples a way to nullify their marriage. One spouse can seek an annulment without the consent or cooperation of the other partner. This might happen if one spouse has been defrauded in some way. For example, his/her spouse may have been untruthful about wanting to have children. This can be difficult to prove since changing one's mind about having children after marriage is not grounds for annulment. Some states automatically nullify marriages in which one spouse was not legally free to marry. This can happen if a person separated from a spouse many years ago but never finalized the divorce. If a couple crosses state lines to avoid parental consent laws regarding underage marriage, the marriage may still be annulled when they return to their home state. Marriages between close relatives can also be subject to annulment.