These days Keira Knightley is rarely seen without boyfriend Rupert Friend by her side. What keeps their relationship of over a year going strong? Perhaps it’s because Keira keeps Rupert on his toes. The 22-year-old actress has allegedly been gushing about her new co-star, Cillian Murphy in order to make Rupert jealous.

An insider told Britain's Daily Express newspaper, "Keira was blown away by Cillian's performance on his latest film Sunshine, and kept going on about it to Rupert and about his beautiful face…She told him Cillian has the most amazing eyes and is an amazing actor.�

Cillian stars with Keira in the upcoming film The Best Time of Our Lives. The source says, "There are a lot of passionate scenes between Keira and Cillian [in the film] so there's plenty of opportunity for Rupert to be hitting the wall if she carries on winding him up like this.�

And the snitch says Keira has an ulterior motive to her gushing. The source revealed, "Keira is a tease and she loves to watch Rupert getting jealous. It's all part of their relationship and they have these spats and then kiss and make up all over again."