reesejakedunzous.jpg We were shocked to learn that Reese Witherspoon and Jake Gyllenhaal had split, but when we saw Jake's assistant moving his stuff out of Reese's Brentwood pad, we knew it was true!

So why did these two end their three-year relationship? Even though Us Weekly initially denied that Reese and Jake had broken up, now they're singing a different tune, stating that the real reason behind the sudden split was Reese's lack of commitment!

A source tells Us, "[Reese] felt pressured to wed again but she wasn't ready. She couldn't give Jake enough and she got cold feet. Jake wanted all of her."

Additionally, Reese questioned Jake's potential as a stepfather and long-term partner. The source said, "He was great with the kids, but she felt like he didn't get the whole scope of what that entailed." Even though there wasn't any drama or cheating, the couple "fought constantly in the past few months," and Reese was concerned that they didn't have enough in common. The source added, "When she was giving all of her energy to Jake, she felt like she wasn't giving her kids enough."

Poor Jake seemed stunned with Reese's decision and the split "broke his heart," but we're sure there's no shortage of ladies (or guys for that matter!) who would be happy to take Reese's place...