Some people get married to sponsor an immigrant so s/he can obtain a green-card. However, when one wishes to terminate the marriage later on, there could be consequences.
The I-130 immigration form generally requires the sponsor to sign an "Affidavit of Support" pledging to financially support the spouse. The consequence is that if the spouse ever applies for public assistance of any sort, the government can use the Affidavit of Support to sue the sponsor to recoup the amount of benefits given to the immigrant spouse. If so, then if a divorce is contemplated, the sponsor spouse should also contact an immigration attorney to terminate the Affidavit of Support.
Bear in mind, the Affidavit of Support may also be used by the immigrant spouse to claim alimony (i.e., maintenance). S/he will argue that the sponsor spouse has already pledged to support him/her, and thus the Court should continue that support by awarding alimony. Finally, one must consider that a divorce may halt immigration proceedings (if they are ongoing), so both parties are well advised to consult an immigration attorney on the consequences of a divorce filing.