Harry Potter co-stars Evanna Lynch and Robbie Jarvis have struck up a romance offscreen.

The actors have been keeping a relatively low profile since the boy wizard film franchise wrapped in 2011, but it appears Lynch, known for her role as Luna Lovegood, and Jarvis, who portrayed a teenage version of Potter's father James, have remained close and they have been sharing photos of their adventures together in multiple photos on social media for the past year.

However, it was only when fans caught sight of Lynch's latest Instagram.com post on Thursday (07May15) that they were alerted to the relationship, as the actress wishes her beau a happy birthday.

In the photo, Lynch puckers up for a kiss as Jarvis smiles into the camera. She captioned the snap, "Happy 29th Birthday to this little babe!! @awildrobbieattacks sweetest boy! Off to see a show together".

The stars have yet to publicly discuss their romance, but Lynch confirmed she and Jarvis are a couple in the caption for an Instagram snap last month (Apr15), in which she referred to Jarvis as her "boyf".