Trump met Melania at a party during New York's Fashion Week in September 1998. He was 52; she was 28.
He came to the party with another woman, but reportedly talked to Melania while his date was in the bathroom.
After seeing Melania for the first time, Trump said he "went crazy." He asked for her number, but she asked for his number instead.
Melania said she felt an immediate connection. "It was great chemistry and energy. We had a great time," she said on CNN in 2005. "We started to talk and something was there right away."
next slide will load in 15 secondsSkip AdSkip AdThe two started dating soon after they met. Melania reportedly struggled with trust issues in the beginning, one of her former roommates in New York told GQ in 2016.
Melania bolstered Trump's image as a playboy. She told radio host Howard Stern in 1999 that they had sex multiple times per day.
Amid Trump's run for president as a Reform Party candidate in 2000, he and Melania separated.
After the breakup, Trump told The New York Times that "Melania is an amazing woman, a terrific woman, a great woman, and she will be missed." A few months later, they got back together.
In April 2004, after dating Melania on and off for more than five years, Trump proposed to her with a 15-karat, $1.5 million diamond ring. She said yes.
next slide will load in 15 secondsSkip AdSkip AdAfter his first two marriages to Ivana Trump and Marla Maples, Trump apparently welcomed Melania's more low-maintenance demeanor. The two were content giving each other space. "I'm not a nagging wife," she has said.
Just like Trump's first two wives before her, Melania reportedly signed a prenup. Gossip columnist Liz Smith said Trump told her, "The beautiful thing is that she agrees with it. She knows I have to have that."
Trump later told the gossip columnist Cindy Adams that his years with Melania "for whatever reasons have been my most successful." "I have to imagine she had something to do with that," he said.
The wedding took place on January 22, 2005, in Palm Beach, Florida, at the Episcopal Church of Bethesda-by-the-Sea. By then, Melania was 34 and Trump was 58.
The couple spent their honeymoon at Mar-a-Lago, the beach resort that Trump owns in Palm Beach, Florida.
next slide will load in 15 secondsSkip AdSkip AdA year later, Melania gave birth to a son. Barron Trump is the couple's only child.
During a 2005 CNN interview, Trump described his relationship as stress-free: "We literally have never had an argument. We just are very compatible."
In another interview with Stern in 2007, Trump said most parenting responsibilities fall on his wife. "Melania is a wonderful mother," he said. "She takes care of the baby and I pay all of the costs."
In June 2015, Trump announced he was running for president.
Melania accompanied him to some campaign events, but largely stayed in New York with Barron while Trump criss-crossed the country holding rallies.
next slide will load in 15 secondsSkip AdSkip AdIn October 2016, an old video surfaced of Trump boasting about being able to grab women "by the p---y." In a statement, Melania said, "the words my husband used are unacceptable and offensive to me" and that they did not represent the man she knows.
After Trump's election victory, one of Melania's friends said Melania didn't want to be first lady "come hell or high water." Melania's communications director denied the allegation, saying she encouraged Trump to run for president.
The couple's marriage has drawn significant interest since Trump took office.
Rumors of discord swirled when Melania didn't move into the White House until five months after her husband's inauguration. She said she wanted Barron to finish out the school year before moving.
On several occasions, Melania seemed to avoid holding hands with her husband. Twitter users and left-leaning media outlets pointed to those instances as signs of a crumbling presidential relationship.
next slide will load in 15 secondsSkip AdSkip AdThe first couple has also had many other loving moments.
Since Melania moved to the White House in June, she has embraced the duties of being a first lady, and appeared at many more official events and trips with her husband.
But in January, news of an alleged 2006 affair between Trump and Stephanie Clifford, a porn star who goes by the stage name "Stormy Daniels," reportedly blindsided Melania and prompted her to cancel upcoming travel plans with her husband. Another woman came forward this week alleging an affair with Trump.
Trump has denied the affair, but it's still unclear what impact the news has had on Melania. The two were married at the time of the purported encounter.
One indicator might have come on Wednesday as couples around the world celebrated Valentine's Day. But the Trumps were notably silent.
next slide will load in 15 secondsSkip AdSkip AdWhile in past years, Melania has posted love notes to her husband on social media, this year she tweeted that she was spending Valentine's Day at the National Institutes of Health.
From the outside, the Trump's marriage seems to be strained. And all eyes will be watching whether the first couple can weather this storm.