When marriage is available to them, few gays choose it
Since May 17, when the imperial order of the Massachusetts Supreme Court took effect, that state has recorded 2,980 marriage licenses to same-sex couples. Of those, 1,985 were to female couples and 995 were to male couples. Massachusettes may have issued as many as 4,266 same-sex marriage licenses, but not all of them have been recorded.
According to the U.S. Census Bureau, Massachusetts has a population of 6,433,422. Of those, 23.6% are under 18. So the state has an adult population of 4,914,598. If we take the conservative assumption that only 2% of adults are homosexual, then the state has a gay population of 98,292. And of those, 6-8% are now married. (If we take the higher, liberal assumption that 10% of adults are homosexual, the percentage of gays in Massachusetts who are married falls accordingly.)
I would think that any pent up demand among same-sex couples for marriage licenses would have been expressed most strongly in the first months following their availability. If so, the figures from Massachusetts are surprisingly small. What's more, we have no reason to believe that lesbians outnumber gay males by a ratio of almost 2:1; so the interest in a marriage license shown to date by Massachusetts' gay male couples is very slight indeed.