‘Til death — or City Hall — do they part.

Marriage can take a beating when you’re mayor of New York because of the “power imbalance” and “resentment,” experts say amid news that Bill de Blasio and Chirlane McCray are dating other people.

The former two-term Democrat mayor and his wife announced they’d remain married, but admitted that ill-advised runs for president and Congress weren’t a romantic elixir.

De Blasio is hardly the first city boss with commitment issues. Only two US presidents — Ronald Regan and Donald Trump — have ever been divorced, and virtually all were in long term unions by the time they got to the White House.

The same can’t be said about most of Gotham’s recent mayors.

Mayor Adams, 62, has never married and spends many a late night out-on-the-town at city hotspots, although he’s in a longtime relationship with rarely-seen girlfriend Tracey Collins.

De Blasio’s predecessor Mike Bloomberg was divorced by the time he got to City Hall. The billionaire was in a domestic partnership with Diana Taylor throughout his three terms.

The thrice-divorced Rudy Giuliani famously announced he was splitting from his second wife at a news conference, leaving it up to reporters to break the news to Donna Hanover.

Ed Koch was a single closeted gay man, reportedly ending a relationship with his boyfriend by the time he was elected in 1978 for fear he would be outed, according to the 2009 film “Outrage.”

Over the last half century, only Abe Beame and David Dinkins enjoyed long-lasting, stable marriages through their tenure.

Four Brooklyn-based couples therapists told Politico why it’s so hard for Hizzoner to remain true.

“It might just be hard to nurture a marriage and give it the energy and commitment it needs, and also devote yourself full-time to the work of the mayor,” Ladi Agahiu, a psychoanalyst, told the outlet Thursday.

“If one person’s job always takes precedence over everything else that’s going on, there’s just no way around it. It’s going to be hard on the relationship,” couples counselor Joseph Teskey reportedly said.

It could also pose problems in a power couple marriage even if the first lady is actively involved with city initiatives, as McCray was.

“Resentment builds for the partners. You have this huge, powerful person and your partner is this intimate person on the sidelines. I don’t see how a relationship could possibly survive,” psychoanalyst Barbara D’Amato said.

However, de Blasio’s marriage to McCray, who used to identify as a lesbian, survived the scrutiny of the press corps for eight years before starting to unravel at the end of his term when the city was the epicenter of the nation’s COVID-19 epidemic — and turf battles with Albany heated up.

“Everything was this overwhelming schedule, this sort of series of tasks,” de Blasio told The New York Times on Wednesday. “And that kind of took away a little bit of our soul.”

Their problems were not unique to high-profile politicians.

Up to 50% of first marriages in the US are estimated to end in divorce, a percentage that grows higher with subsequent marriages, according to World Population Review.

“Marriage and the conceptions of marriage are all changing significantly over time,” psychologist Diana Morozov told the outlet. “Divorce rates are very high in general.”

De Blasio and McCray, who have two adult children together, insist they won’t add to that statistic. The couple planned to remain married and living together, the Times reported.

“We came to this decision together and I think it’s the right decision for us,” McCray explained.