Tom Cruise's adorable daughter Suri (who turns 2 on April 18) makes his life.

"She is Daddy's little girl, and he doesn't know what he'd do without her," a friend of the Cruises tells OK!. "It has been the toughest patch Tom has had since his divorce from Nicole Kidman, Katie [Holmes] has been there for him, of course, and she's his rock, but when you see him with Suri, you just melt. He adores her."

On March 25, Tom and Suri enjoyed some father/daughter time at an L.A. playground.

"I couldn't believe my eyes when I saw them," a parkgoer tells OK!. "Suri was dressed up in this beautiful outfit and was down in the sand playing just like any other kid. Tom was letting her do her own thing, following her around just like any dad would.

"He briefly spoke with a few of the other parents, shook a few hands and exchanged smiles. It looked like he wanted to give her a little playground outing."