Many didn't get approval for annulment as they didnt meet the grounds to do so. The grounds for divorce and the grounds for annulment are different.
Here is the grounds for nullity from AGC statutes:
Grounds on which marriage is voidable
106. A marriage which takes place after 1st June 1981 shall be voidable on the following grounds only:
(a)
that the marriage has not been consummated owing to the incapacity of either party to consummate it;
(b)
that the marriage has not been consummated owing to the wilful refusal of the defendant to consummate it;
(c)
that either party to the marriage did not validly consent to it, whether in consequence of duress, mistake, mental disorder or otherwise;
[21/2008 wef 01/03/2010]
(d)
that at the time of the marriage either party, though capable of giving a valid consent, was suffering (whether continuously or intermittently) from mental disorder within the meaning of the Mental Health (Care and Treatment) Act 2008 of such a kind or to such an extent as to be unfit for marriage;
[21/2008 wef 01/03/2010]
(e)
that at the time of the marriage the defendant was suffering from venereal disease in a communicable form;
(f)
that at the time of the marriage the defendant was pregnant by some person other than the plaintiff.
The grounds for nullity of marriage is not that straightforward and it is better that u talk to a lawyer about it. At least u know what choices u have; nullity, judicial separation first or divorce.
The tricky part is if your marriage less than 3 years. Want to file for divorce for marriage less than 3 years is difficult UNLESS u have very very very strong grounds to do so [ie. unusually cruel adultery (normal adultery would not suffice)] as family law requires you to work things out before using divorce as a solution - this wait-out period is 3 years. Usually, for those who can't file for divorce coz marriage less than 3 years, they would file for separation first (3 years if both parties agreeable, 4 years of one party disagree). Require a lawyer to help draft the deed of separation and lawyer would arrange a Commissioner of Oaths to witness.
Divorce process can be as short as 2-3mths (if both parties are not contesting on the grounds of divorce, matrimonial assets, alimony, child maintenance and custody of kids). Divorce process can drag as long as 3-4 years if either parties contest on any of the matters listed above and despite numerous mediation and trials still could not reach an agreement.