The pair met at California's Coachella Music Festival in April (10) and were often seen together before the singer went public with their romance in July (10).
Their relationship blossomed while Hudson was on the set of the romantic comedy - and Bellamy charmed all of her co-workers.
Egglesfield tells America's OK! magazine, "It looks like they started dating while we were filming. I think her heart was already set on this guy. (Kate) did bring him by the last day of shooting. So, I got to meet him, and he's a cool guy."