The mystery man is 56-year-old former NFL star Radamez Rubio, and according to People, they are newly dating and met while she was on vacation in Mexico a few weeks ago.
"She met him at the hotel she was staying at in Tulum which he was managing and he flew in last week to spend time with her in NYC, Sag Harbor and Connecticut," a source told the publication after the duo was spotted locking lips in the Hamptons over the weekend and canoodling in the city late last week.
"Lu is very happy and is just having a blast spending time with him and taking him to all her favorite spots now that she's vaccinated and everything is open again in NYC and Hamptons," the insider added.
Rubio was a kicker who played for the Miami Dolphins and Pittsburgh Stealers. He also played professional football in Mexico.
Last week, the 56-year-old Countess revealed that she had met a new man in Mexico but did not give up his name.
She inadvertently shared the news when asked on the Chanel in the City podcast what she was looking for in her next partner.
"Well, what I'm looking for, um, actually, you know, I've been, I was in Mexico a lot, and I met a very cute guy from Mexico,” she eventually told host Chanel Omari. "So I would say I want somebody with a lot of integrity, good manners, someone who is loyal, someone who worships the ground that I walk on, and tall, dark and handsome."
"Tall, dark and handsome – and younger!" she added.
She later noted that she was considering taking Spanish lessons "because I like this Mexican guy."
De Lesseps' romance with Rubio comes shortly after she split from her former boyfriend, 49-year-old personal trainer Garth Wakeford, who she met on a dating app late last year.
Although they were hot and heavy for a good hot minute, the former couple eventually ended their relationship somewhat amicably, at least according to Lu.