Emma is currently filming The Perks of Being a Wallflower in Pittsburgh, Pennsylvania where she began hooking up with her 24-year-old costar Simmons.
According to a close source, “They have really fallen for one another and both aren’t dating anyone else".
Meanwhile on the othar hand, Emma Watson has revealed that her on-screen kiss in the movie 'Harry Potter' with co-star Rupert Grint was weird.
"I just had to remind myself, I am an actress. I am Hermione, this is a role – but it was really hard," she said. "We just have so much history together. They are like my brothers, Daily Mail reported.
Emma previously dated financier Jay Barrymore but their two-year relationship ended in March 2010 after two years.