Blue Bloods star Donnie Wahlberg beams alongside Tom Selleck in sweet post

Donnie Wahlberg has a special bond with his Blue Bloods co-stars. Taking to Instagram on Sunday, the actor shared a photo alongside Tom Selleck , which was taken during their reunion at the Paley Centre in New York. "Love this pic," he captioned it, adding a heart emoji.

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Donnie and Tom have worked together since 2010, and during that time they've become close friends.

Appearing on Fox News Digital in February, Donnie, 55, revealed: "Tom Selleck, I call him Dad. At first, he was kind of a little thrown by it for the first season or two, he'd be like, 'Oh, hey, Donnie.' Now it's like, we've gotten so close. He's literally like, 'Oh, hey, son, how are you doing today?'

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"It's like we've just become a real family," added Donnie. "And it's going to be a lot to not be with [them] anymore, but I'm sure we'll stay connected after the cameras aren't rolling."

Tom, 79, has been extremely complimentary of Donnie over the years too, and he was very supportive when the Danny Reagan actor directed an episode of Blue Bloods .

"Donny's a talented man and a talented actor and he brings that to directing, I can already see that" Tom raved to Entertainment Tonigh t . "It's very reassuring for an actor to work with another actor as a director because they get what we do."

While Blue Bloods is set to conclude with season 14B, Donnie and Tom have each shared their sadness over the show's ending.

Joining Andy Cohen on Sirius XM's Radio Andy this month, Donnie recalled his final day on the set. "I felt tremendous gratitude, not saditude, but everyone cried," he said. "Everyone was crying, of course. The last day was heartbreaking.

"It was a lot of emotions. Right? Because, in one sense, the 14 years went by in the blink of an eye. In another sense, it's been 14 years of my life. You know? I didn't even know my wife [Jenny McCarthy] when the show started.

"I remember her visiting me on set in season three, at the end of season three or something like that, and everyone was like, 'What's she doing here?' and all the crew was excited 'cause you know, you get close with your crew and everything," Donnie continued.

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"And so on the last day, I was filming all my squad room scenes and it's kinda like where I hold court as Danny Reagan and Tom Selleck came in just to watch."

"When he shows up to watch you work and to be there to say goodbye to everyone, and like, I'm filming the scenes. I'm already emotional. I look across the room and I see him. He's really tall, and he's standing above everyone in the back corner just watching with tears in his eyes. It just was like the waterworks turned on. I could literally cry just thinking about it."