I thought so but wanted to be sure - it came up New State.
The cause of action for annulment in New York State is generally fraud (DRL §140 (e)).
The grounds for annulment in NY are as follows:
1) If either spouse is incurably incapable of having sexual intercourse, the marriage may be annulled.
2) Both parties must be over the age of 18 years. A marriage between persons under the age of 18 years may be annulled, at the discretion of the Court, if the spouse under 18 wants an annulment.
3) If, after marriage, either partner becomes incurably insane for five years or more, the marriage can be annulled. However, the sane spouse may be required to support the insane spouse for life.
4) The parties must knowingly consent to the marriage. It may be voided if either spouse consents to marry as a result of the force or duress of the other spouse; or either spouse cannot understand the nature, effect and consequences of marriage.
5) The marriage may be annulled where the consent was obtained by fraud, provided the fraud was such that it would have deceived an ordinarily prudent person and was material to obtaining the other party's consent. The fraud must be such as to go to the essence of the marriage contract. Only the injured spouse can obtain the annulment on lack of consent.
In your case the fraud would be based upon the lack of consummation of the marriage and all matters related thereto.
Is it difficult to get an annulment or declaration of nullity?
Yes. It involves a higher degree of proof and many times corroborative evidence from other witnesses is required to establish grounds. That you have evidence of the non-consummation from her along with your testimony and hopefully, hers - you should be able to get the marriage annulled.