I wouldn’t call this “proof”, but the New York Times wrote an article last year about Trump and Epstein’s relationship. According to NYT, Epstein was the one claiming that he introduced them.
https://www.nytimes.com/2019/07/09/us/politics/trump-epstein.html
“But while Mr. Trump has dismissed the relationship, Mr. Epstein, since the election, has played it up, claiming to people that he was the one who introduced Mr. Trump to his third wife, Melania Trump, though neither of the Trumps has ever mentioned Mr. Epstein playing a role in their meeting. Mrs. Trump has said that her future husband simply asked for her phone number at a party at the Kit Kat Club during Fashion Week in 1998.“
(Melania told story about meeting Trump at the Kit Kat Club in a 2017 Vanity Fair profile.)
Also from the above NYT article...
“Roger J. Stone Jr., the former Trump adviser, wrote in his book “The Clintons’ War on Women,” which was published during the campaign, that Mr. Trump “turned down many invitations to Epstein’s hedonistic private island and his Palm Beach home.” Once when Mr. Trump visited Mr. Epstein at his Palm Beach home, Mr. Stone wrote about the scene of underage girls he witnessed there.
“The swimming pool was filled with beautiful young girls,” Mr. Trump later told a Mar-a-Lago member, according to Mr. Stone. “‘How nice,’ I thought, ‘he let the neighborhood kids use his pool.’”