Orchon / Retna Digital 1 / 14
Orchon / Retna Digital 1 / 14

Since Us Weekly broke news last month -- with adorable photo evidence -- of Jason Segel and Michelle Williams' unexpected new relationship, the couple have stayed quiet about their surprisingly serious relationship.

But Segel, 32, finally piped up when asked by "Extra" about Williams, 31.

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"I think we would just very much like to be happy. That's all I'm going to say about it," the actor said alongside his "Five-Year Engagement" costar Emily Blunt.

Blunt herself cooed of Segel's romantic evolution. "He's a man-boy! He used to be a boy-boy, and now he's a man-boy."

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Joked Segel, "I think I might even be becoming a man-man ... potentially!"

In all seriousness, insiders told Us that Segel "has been trying to be more of a grown-up lately" to show his "commitment" to Williams, single mom to daughter Matilda. "He is taking care of himself more, exercising, eating right and dressing better. Basically, not acting like a frat boy anymore."

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Segel and Williams have been friends for years via mutual pal Busy Philipps, and the couple's relationship "kind of happened overnight!" another pal marveled.

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