Just like this post does. Massachusetts was ordered by the supreme court to do this within a 180 day deadline. On the 180th, only after the legislature failed to act in accordance with the court, did Romney issue the order.
"Romney was a leading voice against gay marriage as Massachusetts governor. The courts legalized gay marriage in the state during his tenure, but he supported a constitutional amendment to define marriage as the union of a man and a woman."
-Fox News
From wiki:
"On November 19, 2006, Gov. Mitt Romney led a rally against the tactics that the Massachusetts legislature used to delay and possibly prevent a vote on the same-sex marriage ballot initiative in front of the Massachusetts State House. Romney said he would ask a justice of the state Supreme Judicial Court that week to put the initiative on the ballot in case the legislators failed to vote on the initiative on the last day of the Joint Session, January 2, 2007 as required by the Massachusetts Constitution Amendments Article XLVIII (The Initiative, IV. Legislative Action on Proposed Amendments, Section 2. Joint Session)[17] Romney said, "The issue before us is not whether same-sex couples should marry. The issue before us today is whether 109 legislators will follow the constitution."
On December 27, 2006, the Massachusetts Supreme Judicial Court agreed unanimously with Romney's repeated assertion that Article 48 of the Massachusetts Constitution explicitly and unambiguously requires that the Massachusetts Legislature take a final vote on any and all voter initiatives placed before them, which includes the marriage amendment.
"After gay marriage became legal, Romney sought to enforce a statute banning state officials from marrying gay couples from other states. In a speech to conservatives last winter, Romney touted that move, saying he prevented Massachusetts from becoming the "Las Vegas of gay marriage."
-FoxNews
Read Dr Titus’ letter above in the article.