The point is not whether you have an agreement to annul your marriage, but to show the court that the marriage was invalid at the time when the parties entered into a marriage. The reasons that make a marriage invalid can be:
Bigamous: a spouse or domestic partner is already married or registered as domestic partnership with some one else;
Unsound mind: either party was of “unsound mind” or unable to understand the nature of the marriage or its responsibilities of married spouse;
Fraud: the marriage is a result of fraud. For an example that one get married only to get a green card or hiding the inability to have children;
Force: the marriage is a result of force;
Physical incapacity: it means that 1 of the spouses was physically incapable of “consummating” the relationship and the incapacity continues and appears to be “incurable.