Credit: Kevin Mazur/WireImage

Breakup to makeup!

Justin Timberlake and Jessica Biel might have broken up in March, but a source tells the new Us Weekly (on stands Wednesday) their 4-year-romance hasn't fizzled out just yet.

Timberlake, 30, and Biel, 29, are "quietly seeing each other again," says a source. "They have been talking the whole time and decided to give it another shot. Jessica really wanted to get back together with him and Justin realized single life is not what it's cracked up to be."

On July 3, the couple shared pork tacos at the Black Hoof restaurant in Toronto. But another insider cautions reconciliation won't be easy and adds that for now, "they're just spending time together and taking things slowly."

For more on Justin and Jessica's rekindled romance -- including what obstacles lie ahead -- pick up the new Us Weekly (on newsstands Wednesday).