When Thailand’s long-awaited equal marriage law came into effect on Thursday, police officer Pisit “Kew” Sirihirunchai hoped to be among the first in line to marry his long-term partner Chanatip “Jane” Sirihirunchai.

And he was – they were the sixth couple to register their union at one of Bangkok’s grandest shopping malls, in an event city officials helped organise to celebrate this legal milestone.

Hundreds of couples across Thailand received marriage certificates on Thursday, breaking into smiles or tearing up over the moment they had dreamed of for so long.

It was a pageant of colours and costumes as district officials hosted parties with photo booths and free cup cakes – one Bangkok district was giving air tickets to the first couple who registered their marriage there.

“The rainbow flag is flying high over Thailand,” Prime Minister Paetongtarn Shinawatra wrote on Facebook from Davos where she is attending the World Economic Forum.

Activsts said they were hoping to cross the 1,448-mark for registrations by the end of Thursday – 1448 is the clause in the Thai Civil Code covering the definition of marriage.

“We have been ready for such a long time,” Pisit said. “We have just been waiting for the law to catch up and support us.”

The two men have been together for seven years. Eager to formalise their relationship, they had previously been to a Buddhist monk to give them an auspicious new last name they can share – Sirihirunchai. They had also asked local officials to issue a letter of intent, which they both signed, pledging to get married.

But they said having their partnership recognised under Thai law is what they had been waiting for: “This is perfect for us. The law that protects our rights.”

Until now, official documents listed Pisit and Chanatip as brothers. That way they could be a family in the eyes of the law. A marriage certificate means LGBTQ+ couples now have the same rights as any other couple to get engaged and married, to manage their assets, to inherit and to adopt children.

They can also make decisions about medical treatment if their partner becomes ill and incapacitated, or extend financial benefits – such as Pisit’s government pension – to their spouse.

“We want to build a future together – build a house, start a small business together, maybe a café,” he adds, making a list of all that the law has enabled. “We want to build our future together and to take care of each other.”

The law, which passed in both houses of parliament in June last year before being endorsed by the Thai king in September, is a big step for LGBTQ+ rights.

Thailand remains an outlier in Asia in recognising marriage equality – only Nepal and Taiwan have legalised same-sex unions.

It’s one reason why Aki Uryu, who is Japanese, moved to Bangkok to be with her partner. She said life is difficult for the LGBTQ+ community back home: “In Thailand, I can hold hands with my partner, walk together. No one says anything. It’s just different. It feels right.”

After the two women married on Thursday, Aki said: “It is like I have started my new life.”

Watching them celebrate, along with so many other couples in a Bangkok mall, was Mr Zhang, a gay Chinese man who did not want to reveal his first name.

“We’re excited, we’re also very jealous,” he said. “Thailand is so close to China, but in another sense it’s so far away.”

And yet, even in Thailand, with its famed tolerance towards LGBTQ+ people, activists say it took a sustained campaign to win legal recognition.

“We’ve been waiting for this day for 18 years – the day everyone can recognise us openly, when we no longer need to be evasive or hide,” 59-year-old Rungtiwa Thangkanopast, who will marry her partner of 18 years in May, told the BBC earlier this week.

She had been in a marriage, arranged by her family, to a gay man, who later died. She had a daughter, through IVF, but after her husband’s death began spending time, and later helping run, one of the first lesbian pubs in Bangkok. Then she met Phanlavee, who’s now 45 and goes by her first name only.

On Valentine’s Day 2013 the two women went to the Bang Rak district office in central Bangkok to ask to be officially married – a popular place for marriage registration because the name in Thai means “Love Town”.

This was the time when LGBTQ+ couples began challenging the official view of marriage as an exclusively heterosexual partnership by attempting to get marriage certificates at district offices.

There were around 400 heterosexual couples waiting with them on that day. Rungtiwa and Phanlavee were refused, and the Thai media mocked their effort, using derogatory slang for lesbians.

Still, activists managed to persuade the government to consider changing the marriage laws. A proposed civil partnership bill was put before parliament, offering some official recognition to same-sex couples, but not the same legal rights as heterosexual couples.

A military coup in 2014 which deposed the elected government interrupted the movement. It would be another decade before full marriage equality was approved by parliament, in part because of the rise of young, progressive political parties that championed the cause.

Their message resonated with Thais – and attitudes too had changed. By this time, same-sex marriage was legalised in many Western countries and same-sex love had become normalised in Thai culture too.

Such was the shift in favour of the law that it was passed last year by a thumping majority of 400 votes to just 10 against. Even in the notoriously conservative senate only four opposed the law.

And couples like Rungtiwa and Phanleeva now have their chance to have their love for each other recognised, without the risk of public derision.

“With this law comes the legitimacy of our family,” Rungtiwa says, “We’re no longer viewed as weirdos just because our daughter isn’t being raised by heterosexual parents.”

The new law takes out gender-specific terms like man, woman, husband and wife from 70 sections of the Thai Civil Code covering marriage, and replaces them with neutral terms like individual and spouse.

However, there are still dozens of laws in the Thai legal code which have not yet been made gender-neutral, and there are still obstacles in the way of same-sex couples using surrogacy to have a family.

Parents are still defined under Thai law as a mother and a father. The law also does not yet allow people to use their preferred gender on official documents; they are still stuck with their birth gender. These are areas where activists say they will still need to keep pushing for change.

And it is especially significant for older couples, who have had to ride out the shifts in attitude.

“I really hope people will put away the old, stereotypical ideas that gay men cannot have true love,” said Chakkrit “Ink” Vadhanavira.

He and his partner Prinn, both in their 40s, have been together for 24 years.

“The two of us have proved that we genuinely love each other through thick and thin for more than 20 years,” Chakkrit said. “We have been ready to take care of each other since our first day together. We are no different from heterosexual couples.”

While Chakkrit’s parents quickly accepted their partnership, it took Prinn’s parents seven years before they could do so.

The couple also wanted to share the production business they ran together, and other assets, as a couple, so they asked Prinn’s parents to adopt Chakkrit officially, giving him the same family name. Prinn says the new law has brought welcome legal clarity to them.

“For example, right now when a same sex couple buy something together – a large item – they cannot share ownership of it,” said Prinn. “And one of us passes away, what both have us have earned together cannot be passed on to the other. That’s why marriage equality is very significant.”

Today, said Prinn, both sets of parents treat them as they would just like any other married children.

And when they had relationship problems like any other couple, their parents helped them.

“My dad even started reading gay magazines to understand me better. It was quite cute to see that.”

Additional reporting by Lulu Luo, Paweena Ninbut and Ryn Jirenuwat in Bangkok