WASHINGTON — James Costello called April 15, the day of the Boston Marathon bombings, one of the worst of his life.

“I soon wondered why and for what reason this had happened,” he wrote in a Facebook post, WCVB reports.

But eight months after suffering serious burns to his arms and legs, Costello is engaged to the woman who helped nurse him back to health.

The 31-year-old proposed to nurse Krista D’Agostino during a 10-day European adventure this month with other Boston bombing survivors.

The photos of them on vacation are a stark contrast to the pictures of Costello after the bombing — clothes torn, flesh burned and a dazed look in his eye.

“I’m happy to announce that we will spend the rest of our lives together,” he told the Daily Mail. “I now realized why I was involved in the tragedy. It was to meet my best friend, and the love of my life.”

The two met after Costello was transferred from Massachusetts General Hospital to Spaulding Rehabilitation Hospital.

“A few days later I saw a nurse in passing, this would turn out to be Krista, who had shared a few mutual friends, but we had never crossed paths before,” he told the Daily Mail.

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