The actress made no secret of her relationship as she and her On the Road co-star arrived together at a dinner bash on Monday (23Jan12) for her upcoming movie The Bachelorette.
The couple kissed and hugged and also danced with fellow guests, including actors Will Ferrell, Justin Long and Rashida Jones.
A source tells People.com, "Kirsten and Garrett have been spending time together since the holidays. They were friends on the set of On the Road, and now they've grown closer. They spent Christmas together and he feels very strongly about her."