India, March 20 -- Jennifer Garner and Ben Affleck have been co-parenting their three children for years, but recent public displays of affection have fueled speculation that their relationship might be evolving into something more.

The former couple, who announced their split nearly a decade ago, were spotted at a paintball park in Castaic, California, in early March, celebrating their son Samuel's 13th birthday.

While the two have often been seen together for family-related events, an onlooker at the gathering noted their affectionate interactions, claiming there were "sparks" flying between them. They were "giggling and joking and having a great time with each other," the onlooker told Radar Online.

"It's no secret Ben's been leanin...