AceShowbiz -

Scarlett Johansson and her boyfriend, Nate Naylor, reportedly call it quits after dating for about a year. "She broke up with him last week," a source tells PEOPLE. "He's pretty upset but the writing was on the wall. A lot of people were surprised it lasted this long."

The breakup rumor emerges just a month after ScarJo was spotted getting cozy with her ex-boyfriend, Jared Leto, when they crossed paths at the Democratic National Convention. The actress was seen leaning against the 30 Seconds to Mars frontman while holding hands with him.

Despite the sighting, a representative for ScarJo insisted back then, "Scarlett is still dating Nate. This is very innocent. Scarlett and Jared have remained friends, nothing more, nothing less. Let's concentrate on the DNC and her speech, which is exponentially more important."

The Black Widow of "The Avengers" first stepped out with New York-based advertising creative director Nate in January this year. In an interview with Vogue in April, she praised him for handling the media scrutiny quite well, given that he's not used to dating celebrity.

"It must be very strange for him," the 27-year-old blonde beauty gushed at the time. "It's totally bizarre. It's an adjustment - I mean, it's got to be an adjustment for him way more than it was for me at nineteen. But he's really remarkably good about it."