The 18-year-old, who stars as a directionless high-schooler in the coming-of-age drama, told Digital Spy that he never felt embarrassed filming love scenes with his co-star.
"We had to have good chemistry in reality as opposed to just on-camera for it to work. We certainly got on very well," he said.
"The more intimate moments weren't really embarrassing in any way. Kissing Emma Roberts isn't so bad anyway!"
Highmore revealed that he kept his character George's signature overcoat after filming finished.
"We found it in the 26th Street flea market," he noted. "Emma, Gavin (Wiesen, director) and I went by a couple of days before we finally started filming and picked out the overcoat, and that was the one."
> Emma Roberts, Freddie Highmore The Art of Getting By video interview
Watch Freddie Highmore discuss working with Emma Roberts below: