Sienna Miller, 37, cosies up to beau Lucas Zwirner, 28, during romantic NYC ...

She confirmed her romance with her toyboy art gallery owner in January 2019.  

And Sienna Miller, 37, unveiled a new pink hairdo on Tuesday after enjoying a romantic New York City stroll with her beau Lucas Zwirner, 28, earlier in the day.

The American Sniper star looked effortlessly chic in a pair of flared denim jeans, a beige ribbed top and oversized trenchcoat. 

New look: Sienna Miller , 37, unveiled a new pink hairdo on Tuesday after enjoying a romantic New York City stroll with her beau Lucas Zwirner, 28, earlier in the day

New look: Sienna Miller , 37, unveiled a new pink hairdo on Tuesday after enjoying a romantic New York City stroll with her beau Lucas Zwirner, 28, earlier in the day

Taking centre stage was Sienna's new hairdo as she showed off her new pastel pink locks, a stark contrast to her usual signature blonde tresses. 

The actress finished her chic ensemble with a burgundy handbag and a pair of Gucci trainers. 

Earlier in the day, Sienna had sported her usual signature blonde locks as she enjoyed a romantic stroll with her toyboy love Lucas. 

The star cut a casual figure in a pair of black knitted leggings and an oversized beige jumper.  

Earlier in the day: Just hours before, Sienna had sported her usual signature blonde locks as she enjoyed a romantic stroll with her toyboy love Lucas (pictured)

Earlier in the day: Just hours before, Sienna had sported her usual signature blonde locks as she enjoyed a romantic stroll with her toyboy love Lucas (pictured) 

Pretty in pink: Taking centre stage was Sienna's new hairdo as she showed off her new pastel pink locks

Signature look: It was a stark contrast to her usual signature blonde tresses (pictured earlier in the day)

Pretty in pink: Taking centre stage was Sienna's new hairdo as she showed off her new pastel pink locks, a stark contrast to her usual signature blonde tresses (pictured earlier in the day, right) 

Chic: The American Sniper star looked effortlessly chic in a pair of flared denim jeans, a beige ribbed top and oversized trenchcoat

Chic: The American Sniper star looked effortlessly chic in a pair of flared denim jeans, a beige ribbed top and oversized trenchcoat

Dressing for the cool weather, Sienna teamed the items of clothing with a pair of shearling knee-high boots with black ties around them.

The actress accessorised her look with a gold bracelet, burgundy handbag and oversized brown sunglasses. 

Sienna left her blonde locks loose into a relaxed hairdo as she added a slick of minimal make-up to enhance her

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