Japan’s Princess Mako has lost her royal status after marrying her “commoner” college sweetheart, Kei Komuro – a man she described as “irreplaceable” – in a modest ceremony.

After years of criticism of their relationship that has left Mako struggling with her mental health, Emperor Naruhito’s niece and Komuro announced at a press conference in Tokyo on Tuesday they had wed. They declined to take questions from reporters.

The couple, who met at university almost a decade ago, were originally due to marry in November 2018 but postponed after Japanese media revealed that Komuro’s mother was embroiled in a minor financial scandal.

On Tuesday Komuro voiced regret at how his mother’s troubles had overshadowed the wedding preparations. Of his bride, he said: “I love Mako-san. And I would like to spend my life with the person I love.”

He said he would do “everything possible” to resolve the financial dispute between his mother and a former fiance from whom she reportedly borrowed JPY4m, although there have been claims that the money was a gift.

Intense media coverage of his family and scrutiny of the couple’s relationship has taken its toll on Mako. The imperial household agency recently revealed she was suffering from complex post-traumatic stress disorder.

Her health was reportedly behind the couple’s decision to make a statement on Tuesday and hand out written answers to reporters’ questions rather than respond verbally.

Mako said her decision to marry Komuro had been a “necessary choice”. While she acknowledged that some members of the public opposed their union, she said they planned to spend their lives together “cherishing and protecting our feelings”.

Referring to Mako’s condition, Komura said: “Incorrect information was treated as if it were true, and I am very saddened that Mako-san has had problems with her physical and mental health as a result of defamatory remarks.”

The couple did not have a formal wedding ceremony or hold a reception banquet or any of the traditional rites associated with imperial weddings.

Her father, Crown Prince Akishino, had reportedly opposed a traditional royal wedding after acknowledging that the Japanese public were divided over their marriage in light of reports that Komuro’s mother had failed to repay the loan, some of which went on her son’s education.

In a survey for the Yomiuri newspaper, more than half of respondents were positive about the marriage and a third were not.

Mako, who gained a master’s degree from Leicester University, turned down a payment of about JPY140m ($1.23m) of taxpayers’ money that is traditionally given to women who renounce their royal status when they marry.

TV footage showed Mako leaving her family home, the Akasaka imperial residence, on Tuesday morning. Dressed in a pale blue dress and holding a bouquet, she bowed to her parents and hugged her younger sister, Kako.

Japan’s male-only succession laws mean Mako can never be a reigning empress. If she has a son he will be raised as a non-royal and will not ascend the Chrysanthemum throne.

Her departure from the palace has highlighted the dearth of heirs to the throne, while pressure to reform the succession laws has failed to gain traction under successive conservative governments. Mako’s father is first in line, followed by her younger brother, Prince Hisahito. If Hisahito does not have a male child, the line of succession will be broken.

Experts said her father and brother’s key positions in the imperial line had fuelled public opposition to her marriage to Komuro. “Although it’s true that [Mako and Komuro] will both be private citizens, Mako’s younger brother will one day become emperor, so some people thought anybody with the problems Komuro had should not be marrying her,” said Hideya Kawanishi, an associate professor of history at Nagoya University.

Mako and Komuro plan to move to New York, where Komuro works for a law firm. The couple did not see each other for three years until Komuro’s recent return from the US, and will again be separated while Mako remains in Japan to prepare for the move and apply for her first passport.