Another couple splitting up...?

Rumor has it that Scarlett Johansson and Josh Hartnett may be close to calling it quits.

According to one source, "They are on the rocks, Scarlett is always mad at him, and they are always arguing."

Apparently, distance might be taking it's toll on their relationship - they are each filming in different locations blah blah.

Could that mystery audio 'sex tape' have been a part of this? hmmm....