Annulments are rarely granted and when they are, very specific circumstances must exist. Annulment refers only to making a voidable marriage null; if the marriage is void ab initio, then it is automatically null, although a legal declaration of nullity is required to establish this.A marriage can be declared null and void if certain legal requirements were not met at the time of the marriage. If these legal requirements were not met then the marriage is considered to have never existed in the eyes of the law. This process is called annulment. It is very different from divorce in that while a divorce dissolves a marriage that has existed, a marriage that is annulled never existed at all.
Section 12 of Hindu Marriage Act, 1955 deals with
Voidable Marriages- (1) Any marriage solemnized, whether before or after the commencement of this Act, shall be voidable and may be annulled by a decree of nullity on any of the following grounds, namely:-
(a) that the marriage has not been consummated owing to the impotency of the respondent; or
(b) that the marriage is in contravention of the condition specified in clause (ii) of Section 5; or
(c) that the consent of the petitioner, or where the consent of the guardian in marriage of the petitioner was required under Section 5 as it stood immediately before the commencement of the Child Marriage Restraint (Amendment) Act, 1978, the consent of such guardian was obtained by force or by fraud as to the nature of the ceremony or as to any material fact or circumstance concerning the respondent; or
(d) that the respondent was at the time of the marriage pregnant by some person other than the petitioner.
2) Notwithstanding anything contained in sub-section (1), no petition for annulling a marriage-
(a) on the ground specified in clause (c) of sub-section (1) shall be entertained if-
(i) the petition is presented more than one year after the force had ceased to operate or, as the case may be, the fraud had been discovered ; or
(ii) the petitioner has, with his or her full consent, lived with the other party to the marriage as husband or wife after the force had ceased to operate or, as the case may be, the fraud had been discovered;
(b) on the ground specified in clause (d) of sub-section (1) shall be entertained unless the court is satisfied-
(i) that the petitioner was at the time of the marriage ignorant of the facts alleged;
(ii) that proceedings have been instituted in the case of a marriage solemnized before the commencement of this Act within one year of such commencement and in the case of marriages solemnized after such commencement within one year from the date of the marriage; and
(iii) that marital intercourse with the consent of the petitioner has not taken place since the discovery by the petitioner of the existence of the said ground.
So in your case you have to prove marriage is not consummated due to your wife's refusal for sex.