Sources say the two were “very close” at the NYC film premiere

Saoirse Ronan, busy doing press for her latest film ‘Mary Queen of Scots,’ is reportedly cozying up with a co-star this Christmas season.

Read More: Saoirse Ronan breaks new ground in "Mary Queen of Scots"

Page Six reports that Ronan is dating her co-star Jack Lowden, and the two were nearly inseparable at their New York premiere of ‘Mary Queen of Scots.’

A source told Page Six: “Jack was following her all over.”

“He even followed her to the bathroom and was waiting outside for her. They were very close.”

Ronan and Lowden play wife and husband in the new film ‘Mary Queen of Scots,’ which also features Australian starlet Margot Robbie. The film is already generating Oscar buzz.

Jack Lowden and Saoirse Ronan in Mary Queen of Scots (IMDB)

Jack Lowden and Saoirse Ronan in Mary Queen of Scots (IMDB)

28-year-old Lowden starred in 2017’s ‘Dunkirk’ and won a BAFTA Scotland for his turn in 2018’s ‘Calibre.’

Read More: Saoirse Ronan and Jimmy Fallon’s Irish up Christmas with a cover of “Fairytale of New York”

A movie source told Page Six: “We don’t know when they got together, we only found out on Tuesday night when they rolled up together — but they seem very happy and sweet.”

Prior to filming ‘Mary Queen of Scots,’ Lowden said: “she’s lovely . . . I can’t wait for that it’s going to be fun.”

Joining Ronan and Lowden at the NYC premiere was Ronan’s doting Irish mammy Monica, says a source.

Ever the celeb, Ronan had to leave the premiere party a bit early to continue her work on Greta Gerwig’s upcoming adaptation of ‘Little Women’ in which Ronan stars as Jo March. The film includes other A-listers Emma Watson, Meryl Streep, and Timothée Chalamet.

Read More: WATCH: Saoirse Ronan answers the Internet’s most popular questions about her

Ronan and Gerwig previously worked together on the critically acclaimed Ladybird, which was nominated for five Oscars.

Catch the trailer for 'Mary Queen of Scots,' which is in theaters today:

Cast of 'Mary Queen of Scots' at the New York City film premiereGetty