Lady Gaga and Taylor Kinney are now happily engaged, but their relationship first got off to a rocky start. Last night the "Chicago Fire" actor joined Andy Cohen on Bravo's "Watch What Happens Live" and told the host the tale of his first interaction with Gaga.

The pair met on the set of the music video for Gaga's song "You and I" in 2011 where Kinney, 34, played her love interest.

"I remember I went up, and we're rolling, and I kissed her and she didn't expect it," Kinney explained. "They cut, and she slapped me. And then it was just awkward. And then the next take, I just did it again and then she didn't slap me. She didn't slap me then."

Kinney and the "American Horror Story: Hotel" actress got engaged last Valentine's Day and confirmed the news on Gaga's Instagram account.

"He gave me his heart on Valentine's Day, and I said YES!" she captioned the picture of her beautiful heart-shaped engagement ring.

While Gaga did slap Kinney the first time, they both recognized the chemistry as the music video shoot continued.

"It was a late shoot. We were shooting until 4 or 5 in the morning - something like that. We exchanged information," Kinney said. "A few weeks went by and we kept in touch and then that's that."

While the couple has been engaged for a couple of months now, Kinney said they have not made any wedding plans yet, according to Us Weekly. 

Kinney's show "Chicago Fire" airs Tuesdays at 10/9c on NBC and Gaga's "American Horror Story: Hotel" airs Wednesday's at 10/9c on FX.