There are many reason why some would prefer an annulment. When you examine the the legal basis or reasons the court will grant an annulment, it is little wander that an annulment is preferable to a divorce. An annulment invalidates or treats the marriage as if it never occurred.
Additionally, some annulments are based upon religious grounds, with Roman Catholics leading the way. My understanding is that it requires a someone who is a "Canon" lawyer and not an area I have ever delved into.
On the other hand, a legal annulment in Pennsylvania includes two distinct types: marriages that are "void" and ones that are "voidable." Both are based upon certain circumstances which are impediments to the formation of the marriage.
In order to obtain an annulment based upon circumstances that make the marriage void there can be no further cohabitation after the other learns of the the impediment. Reasons for a void marriage are:
One of the spouses was married to another person. This can occur when one party is deceptive, or if one party believes thy have been properly divorced and they have not.
The parties are blood relatives. The law speaks in terms of "degrees of consanguinity" which prohibit a person from marrying their parent or grandparent, brothers and sisters, aunts and uncles and first cousins.
Insanity and Mental Disorder. Pennsylvania law allows for annulment's when a mental condition renders one of the parties incapable of consent. Here the issue is whether the person had the mental capacity to enter into a marriage.
One of the Parties to a purported common law marriage was under 18. This one is still on the books but since common law marriage has been abolished, not a likely situation.
Voidable Marriages are ones that can become valid. If circumstances provide for this type of annulment, the marriage is voidable from its inception. Grounds or reasons for an annulment of a voidable marriage include:
When on of the spouses was under 16 years of age and the marriage was not expressly authorized by a court.
When either party was 16 or 17 and lacked parental consent or court approval and the marriage was not later ratified upon reaching age 18 and the action (the court case) was commenced within 60 days of the marriage.
Where one of the spouses was under the influence of alcohol or drugs and the action was commenced withing 60 days of the marriage. This is the classic waking up in Vegas after too much liquor to find out your married.
Where one party was induced to marry by fraud, duress, coercion or force and there has been no later voluntary cohabitation after knowledge of the fraud or release from the effects of the fraud, duress, coercion or force.
In all cases of "voidable" marriage, it is considered valid until an annulment is obtained from a competent court. Also, a voidable marriage cannot be attacked or questioned by anyone if the marriage has been confirmed by the parties. It also can't be questioned after one of the parties dies.
So, unless of these very narrow set of circumstances exits, a person is not likely to be able to obtain an annulment...they are difficult, but not impossible.
The alternative is a divorce, and with no-fault divorce being the law of Pennsylvania, there is still a way to dissolve a marriage, but that's the topic for another day.