Harry Potter star Evanna Lynch had a nine-year relationship with her co-star

Harry Potter star Evanna Lynch had a nine-year relationship with one of her co-stars after meeting him on set.

The 31-year-old is best known for her role as Luna Lovegood in the Harry Potter franchise after joining the cast back in 2007 on Harry Potter and the Order of the Phoenix.

And it was on the fifth instalment of the popular series where Lynch met Robbie Jarvis, who played a younger version of Harry's father James.

Warner Bros / PictureLux / The Hollywood Archive / Alamy Stock Photo

However, Jarvis' time in Harry Potter was very brief as he only appeared during a flashback scene in Harry Potter and the Order of the Phoenix.

In this short scene, Jarvis' character can be seen laughing as he uses a spell to disarm a young Severus Snape.

Lynch and Jarvis formed a close bond during their time on set and secretly dated until 2015.

Then, the couple decided to go public with their romance in a series of Instagram posts.

As per The Mirror, Lynch captioned a picture of Jarvis on social media in May 2015 with: "Happy 29th Birthday to this little babe!! Sweetest boy! Off to see a show together #happybirthdayrobbie."

Photos were also shared to Instagram from a trip to Hobbiton in New Zealand, where the Lord of the Rings movies were filmed.

In these posts, it was revealed that Jarvis had eaten meat for the last time on that trip as Lynch persuaded him to go vegan.

Everett Collection Inc / Alamy Stock Photo

After being surrounded by sheep at a tourist attraction, Lynch was not best pleased to discover that Jarvis was planning to order a lamb burger for lunch.

As a result, she began educating her boyfriend on the benefits of a plant-based lifestyle.

Jarvis said: "That holiday was the last time I ate meat and I pity the boy in this photo who had more in common with those sheep than he realised.

"I'm happy to say that I'm now much closer to knowing the true cost of my food."

The pair went their separate ways in 2016. REUTERS / Alamy Stock Photo

However, the pair sadly split in 2016, though they did remain close friends.

Speaking at the premiere of Fantastic Beasts and Where To Find Them, Lynch said: "We're both vegans, so we go to a lot of vegan events together. So yeah, we're good friends."

In 2020, Jarvis posted a birthday snap of Lynch on a boat in a river.

He wrote: "Happiest of birthdays to someone who is always delighted to see ducklings!"