Josh Groban and Kat Dennings Have Everything in Common, Except This

— -- Before Josh Groban performed on the Tony Awards on Sunday night, he walked the red carpet with his girlfriend of several months, Kat Dennings.

Dating the singer has meant a crash course in musical theater for the "2 Broke Girls" star.

"We’ve had fun when we’re in New York. I’ve taken her to see shows like 'Gentleman’s Guide to Love and Murder,'" Groban told ABC News. "We both love Monty Python, and so for us to see a show that has so much incredible British slapstick humor in it and great really fun songs, that was fun. So, I think she’s coming over to this side a little bit."

For Groban, 34, getting to introduce Dennings, 28, to something new has been exciting.

"When you literally have like 99 percent of things in common, it’s really nice when you both have kind of interests that are different in certain ways," he said. "So she didn’t grow up with the musical theater exposure that I did, and so her opinion about it I think was pretty much based on that. And certainly not all musicals are everybody’s thing."

She also has been weighing in on Groban's latest album, "Stages," a collection of songs from musicals.

"I think she really likes the album too, so that makes me happy," he said.