Is this 28-year-old Harvard PhD student Andy Cohen's boyfriend? Clifton Dassuncao goes on second vacation on Barry Diller's yacht with Bravo host in just three months

Andy Cohen took a vacation on billionaire Barry Diller's yacht last week, and for the second time in three months was joined by the same young man.

Clifton Dassuncao, 28, a fellow in Environmental Science and Engineering at Harvard University, was photographed with Cohen, 47, during the trip in a shot posted to Instagram by The Palms owner Bruce Bozzi, who is the Bravo host's best friend.

'Hello Thursday! Yesterday's afternoon adventure!!!' wrote Bozzi on the photo the showed himself and partner Bryan Lourd, Diller and wife Diane von Furstenberg, producer Jason Blum and his wife Lauren and Cohen and Dassuncao.

Cohen was wearing a City Sports Boston shirt the photo, the city where Dassuncao lives. 

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Andy, 47, donned a shirt from Boston along with a hat from Barry Diller's yacht while on vacation last week - and he was standing next to a mystery man who lives in Boston - but his identity is a mystery no more

Cohen took a couple's vacation last week in the Caribbean on a megayacht belonging to Barry Diller (in green t). Also on the tropical getaway was Bruce Bozzi, third from left, his super agent partner Bryan Lourd, far right, Diller's wife Diane von Furstenberg and the Blums. Next to Andy is his friend Cliff

Clifton Dassuncao, 28, is a Harvard graduate student  who has known Andy since last summer at least - when he and a friend went to a taping of Cohen's Bravo show Watch What Happens LIve

Shortly after he visited Watch What Happens Live, he shared his end of summer reading list - which included Cohen's book checked out of the library

After Christmas - both Andy and Clif were on Diller's yacht in the Caribbean. This post of Clif's from Guadeloupe about '#monkeybusiness' even garnered a comment from Cohen - aka Bravoandy. After being asked for comment on this story by DailyMail.com, he turned his public Instagram feed private

Andy was in Guadaloupe at the same time on Diller's boat - as seen here with an Eos crew member 

Dassuncao previously posted photos of himself on Diller's yacht last December, including one photo where he wrote; '#monkeybusiness.'

Cohen commented on that photo; 'Monkey business is right.' 

The yacht was docked off of Guadeloupe in the French West Indies that day, the same place were Cohen was posting photos.

Dassuncao, whose family lives in New York, first posted a photo of himself and Cohen in July after seeing him on Watch What Happens Live.

'This happened, live,' wrote Dassuncao. 

A week later he posted a photo on Instagram of his summer reading list which included a copy of The Andy Cohen Diaries, which Cohen liked.

Dassuncao is one of the only 259 people Cohen, who has 1.5million followers, follows on Instagram.

In addition to the group shot over their most recent vacation together, Dassuncao was also tagged in a photo of the group having lunch with Kelly Ripa and Mark Consuelos.

Ripa's children and producer Sandy Gallin were also at the lunch.

During last week's spring break getaway, the young scholar also got to hang out with Cohen's friends Kelly Ripa and Mark Consuelos and friends when they visited them on Mustique. Clif is peeking out second from the end on the left side sitting next to Sandy Gallin

The December trip also stopped in the Grenadines where both men shared photos

On the Christmas trip both posted plenty of bathing suit photos - but never shared a group photo

Dassuncao has an incredibly impressive resume, having worked for the Centers for Disease Control and Prevention and the U.S. Geological Survey in addition to his research at Harvard, according to his Linked In. 

Dassuncao is getting his PhD from Harvard

He grew up in Queens and attended private school in New York City at Loyola on the Upper East Side 

He then went off college at the Massachusetts Institute of Technology. 

After college he stayed in Boston and received his Master's Degree from Harvard.

His Instagram page was just created last year and most of the photos are of him out with friends in Boston.

In one photo, he and two friends wear nothing but Santa caps and Speedos as they prepare for the annual Santa Speedo run in Boston.

In another he poses in his Halloween costume while out in New York City last year.

Wearing overalls and a mask, he sits on a dumpster in the picture, which reads; 'Cleaning up this city one body at a time. #dump'

He also posted a throwback photo around that time of himself and a friend dressed as Mario and Luigi from Super Mario Brothers. 

"#tbt to when we had to #hustle for that coin,' wrote Dassuncao on the photo. 

After repeated requests for comment from Cohen's reps at NBC and Bravo, Dassuncao set his Instagram account to private on Thursday afternoon.

Fit: Dassuncao, far right,  and his friends pose for a photo before the Santa Speedo run in Boston in December

Fun loving: For a throwback Halloween picture Dassuncao shared this photo of himself and a friend dressed as Mario and Luigi

School spirit: "#winning #yuckfale,' wrote Dassuncao on this photo of himself and friends from Harvard

Dassuncao made his instagram account private shortly after noon on Thursday after Cohen and his reps were asked for comment

Cohen has always kept quiet when it comes to his love life and sexual escapades, though he has admitted to hooking up with Lance Bass and been very clear that he and friend Anderson Cooper have never dated or had sex.  

He lives in the West Village with his dog Wacha. 

Reps for Cohen had no comment about his relationship with Dassuncao.