and ’s relationship is growing stronger.

Things are “going really well” for the actor-director, 48, and the model, 28, a source tells PEOPLE. 

“They are getting more and more serious,” the source says. “Gigi’s been spending time in Philadelphia with Bradley too.” 

Adds the insider: "They were pretty low-key when they were in town recently and had a date night in a private room at a local restaurant. They were quietly dating for much longer and were very hush-hush, trying to see if things would work between them. They had several months together privately and things have been going really well.

"

The pair sparked romance rumors after being spotted having dinner together at in New York City's West Village in October. 

"They are having fun," a source told PEOPLE at the time. “It appears super casual now, but they both have kids, big careers, busy lives and understand what life is like in these circles,” the source added. “It’s cute … and there is an attraction.”

Since then, the couple has been spotted out with one another on multiple occasions. 

Hadid was recently present to show her support when the

actor had New York City earlier this month. 

“Good afternoon, bread heads,” Cooper said with a smile in an video shared by Angelo's Pizzeria on Dec. 6. “Come on down, get a cheesesteak!”

The star partnered with the eatery’s owner Danny DiGiampietro to open Danny and Coops Cheesesteaks. Hadid was photographed standing at the front of the food truck line.

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Cooper’s ex, , stopped by as well with the former couple’s 6-year-old daughter Lea De Seine. 

Hadid also has a child, her 3-year-old daughter who she shares with her ex . 

Last month, a source told PEOPLE that Hadid "enjoys" dating Cooper.

"Her daughter will always come first," the source said. "She loves that Bradley is a dad, because he gets it. than guys she dated in the past. They keep spending a lot of time together. They have dinner dates several times a week. It makes her happy."

The source went on to say that the model doesn't date "just to date," but is dating Cooper because she "finds him interesting and attractive.

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