Kristen Bell & Dax Shepard
07/02/2012 at 06:00 AM EDT
Apparently Kristen Bell
and Dax Shepard can't get enough of each other.
Aside from living together, Bell also stars in Hit & Run
, a film directed and written by Shepard – and when they came out to a special screening of the movie on Wednesday at the Downtown Independent Theater, it was clear the engaged couple
's flame has not died down.
During the Q & A for screening guests, "Dax lifted Kristen up and gave her a really affectionate kiss," an onlooker tells PEOPLE at the Brancott Estate Wines-hosted viewing. "At one point, Dax said to her, 'Shouldn't you be saying something really adorably cute right now? You're so good at that.' "
The source adds that Bell, who shared soda and popcorn with her fiancé until the screening started, told the audience having him as a boss was tough because, "If you think Dax Shepard the actor is cute, you wouldn't be able to handle it!" – Dahvi Shira