Mr. Johnson, who was baptized as a Catholic by his mother, converted to the Anglican faith while in boarding school. He met Ms. Symonds, a Catholic and a former Conservative Party communications aide, while he was married to his second wife, Marina Wheeler, with whom he has four children.
Mr. Johnson has never publicly confirmed how many children he has.
Mr. Johnson and Ms. Symonds disclosed that they were engaged, and that she was pregnant, in February 2020, a month after Britain had formally left the European Union. That happy news was quickly overtaken by the pandemic, which claimed Mr. Johnson as an early victim when he became ill and ended up in an intensive care unit.
Ms. Symonds, who works for an animals-rights group, also contracted Covid and wrote on Twitter about her fears during those days.
More recently, she has been pulled into a furor over the costly renovation of the couple’s apartment at 11 Downing Street. A Conservative Party donor, David Brownlow, paid for some of the work, supplementing the state budget of 30,000 pounds, or $42,570, provided for redecorating the apartment. Mr. Johnson said he had picked up the cost of the refurbishment when he was told of the arrangement.
On Friday, an independent ethics adviser appointed by the government declared that Mr. Johnson had acted “unwisely” in the refurbishment of the apartment but that he had not violated the ministerial code of conduct.