OLYMPIA, Wash. (AP) _ Matt Fleming has considered himself a married man ever since he and his partner, Casey Jackson, had a 2007 commitment ceremony in Spokane that was attended by 400 people. On Monday, the state makes it official.

Fleming, 38, and Jackson, 47, will be among thousands of registered domestic partners who will start the week married in the eyes of the state, under a component of Washington's same-sex marriage law that was approved by voters at the end of 2012. A provision of that law converts all same-sex domestic partnerships _ in which both partners are under 62 years old _ to marriage on June 30.

Fleming said that while he knows of a few friends who were frantically getting out of their domestic partnerships before the automatic conversion, ``doing a domestic partnership, for me, was just like getting married.''

``I took it really seriously at the time,'' he said.

Fleming, an administrator at a nursing home, said that he and Jackson talked about getting married and having a big party after the 2012 law took effect. But the busy fathers of 5-year-old twins, Bella and Lilah, said that their plans got away from them.

``Then we found out that we could automatically roll over and it was like `well, that saved us a step,'' Fleming said. Now, ``we might have a barbecue.''

Washington state's first domestic partnership law passed in 2007, granting couples about two dozen rights, including hospital visitation and inheritance rights. It was expanded a year later, and again in 2009, when lawmakers completed the package with the so-called ``everything but marriage'' bill that was later upheld by voters.

Before same-sex marriage became legal in Washington state, there were nearly 10,000 domestic partnership registrations with the secretary of state's office. Now, more than 6,500 such partnerships remain, and about 1,200 have been terminated. More than 7,000 same-sex couples have been married since the end of 2012, though not all of them were previously domestic partners.

Beginning Monday, domestic partnerships, for heterosexual and gay couples, can only be filed if one partner is 62 or older. That provision was included in the state's first domestic partnership law of 2007 to help heterosexual seniors who didn't remarry out of fear they could lose pension or Social Security benefits.

The secretary of state's office, which oversees domestic partnership registrations, started sending letters to same-sex domestic partners last year, and again in March, telling them about the change and what to do if they wanted to dissolve their partnership before the marriage conversion.

``Our phones lit up,'' said Pam Floyd, corporations director for the secretary of state's office.

Floyd said that in spite of the state's efforts, there will inevitably be a few people who have broken up without officially dissolving their partnership and maybe moved to another state and don't realize they will soon need a divorce to officially end their relationship.

``They're living quiet lives someplace and don't know all of this is happening,'' she said.

Same-sex marriage is legal in 19 states and the District of Columbia, though there's a wide variance on how those states that previously had domestic partnerships or civil unions integrated their laws.

For example, New Hampshire and Connecticut automatically converted civil unions to marriages, but New Jersey did not, and civil unions remain an option there, as do domestic partnerships for opposite-sex couples who are age 62 and older. In California, domestic partnerships remain an option.

The Department of Health will be the agency that officially converts the partnerships of those who have not married or terminated their partnership in Washington state. Floyd said the secretary of state's office has been working to update the partnership data as they hear from couples, but estimated that between 3,000 and 4,000 conversions will occur and about 2,000 will remain domestic partners due to age provisions.

Rick Sipe, who has been with his partner, Dan Neish, for 18 years, said that he was disappointed to learn that the domestic partnership they've had since 2007 won't automatically be converted to marriage because Sipe is 64.

``We're a couple that actually wants to wake up married and the state says `nope, you have to go do this,''' Sipe said.

Because they've had a full calendar of attending weddings of friends who were rushing to have ceremonies before the state's automatic conversion, the couple has decided to hold a small wedding ceremony at their home on July 16, with friends hosting a larger reception two days later.

Sipe and Neish, 57, have bought their wedding rings and received their marriage license.

``It's wonderful, but it's a little overwhelming,'' Sipe said. ``We grew up in a world where neither one of us expected to be married, ever. The idea of being husbands wasn't in our vernacular.''