The New 'It' Couple? Blake Lively and Leonardo DiCaprio Romance Details

Hot on the heels of the photo released of Blake Lively and Leonardo DiCaprio holding hands in Monte Carlo, a seemingly sure sign that the two indeed are a couple, ET chatted with Us Weekly Senior Editor Bradley Jacobs.

"On May 27, Leo and Blake went on a moonlit stroll in Monte Carlo and an onlooker says that Leo looked very excited," Jacobs dishes to ET. "Other sources say they have great chemistry and that they are both flirtatious and very captivating people."

Blake, who's been making headlines lately for nude photos surfacing that her rep says are 100 percent fake, reportedly first met Leo at a business meeting back in November. She later reconnected with him at a birthday party in January for Jeremy Renner, her co-star in 'The Town.' Reportedly, this is when the two first kissed. Then in May, the pair had shutterbugs in a frenzy when they were photographed hugging on Steven Spielberg's yacht at the Cannes Film Festival.

According to Jacobs, Leonardo has been in "hot pursuit" of Blake for weeks.

"We now have the proof," Jacobs says. "These are the photographs of Blake and Leo holding hands, and they are clearly smitten."

Both of the megastars recently split from their longtime loves. Leo broke up with on and off girlfriend Bar Refaeli just this spring, and she split with her "Gossip Girl" co-star Penn Badgley last October.

"One insider says that Bar and Leo hardly ever saw each other, but when they did they would fight," Jacobs says. "But things seem completely different with Blake. Another insider says that he seems completely smitten with her."

Another source says Blake has had a crush on Leo dating back to his 'Titanic' days. She was 10 years old when 'Titanic' came out, and he was 23 when the epic movie that made him a household name was released. Now of course, she's the one who's 23 with her budding career taking off, and Leo is still a bachelor at 36.

But although Blake has reportedly been crushing on Leo for a long time, apparently it's Leo who's doing everything he can to woo her.

"He's taken her on helicopter rides, dinners, yachts and he's even holding doors for her," Jacobs says.

"I've never seen him like this with a girl," adds a DiCaprio insider.