"I keep that stuff to myself," Jonas, 18, told PEOPLE shyly when asked about his dating life.
But the musician, who is playing Marius in a special concert production of musical, was more forthcoming when asked about British women in general. "They're great – very kind," he said, "[and] very supportive."
Barks, 20, who plays Eponine in the show, started giggling when Jonas's name came up – though she had plenty of nice things to say about her costar.
"Nick is such a wonderful person," she told PEOPLE. "Yeah, we definitely keep in contact."
Dancing and walking around the party hand-in-hand, the two mingled with Kevin Jonas and his wife Danielle, as well as Joe Jonas and his new girlfriend Ashley Greene, who frequently snuck smooches in between tunes.
The group goofed around on the dance floor at IndigO2 to pop songs by Katy Perry and the cast of Glee.
While fun was the theme of the evening – the group stayed until about 1 a.m. – the younger Jonas is also focused on his work."Right now I'm busy working and I feel so blessed to be here," Nick said. "To play Marius in this show has been a dream come true for me."
Would Jonas ever consider settling down like his married, older brother Kevin?
"I could definitely see myself doing that," he said, "as long as it's the right time and the right person."