OK! EXCLUSIVE: Behind Jenny & Jim's Split

When Jenny McCarthy and Jim Carrey announced calmly over Twitter last week that they had decided to end their relationship, many people were shocked. And in a time when every celeb break-up seems to involve another woman (or you know, 16 others), Jim and Jenny's friendly break seemingly came out of nowhere. A friend close to Jenny tells OK! that behind the scenes, when the end arrived, it was relatively simple.

"Jenny said it became very Jerry McGuire-esque, in the sense that she had this had this great guy, and he loved her kid, but they were no longer hitting their stride," the insider tells OK!. "She said when she and Jim worked, they worked — and when they stopped working, it was done, just like that."

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According to Jenny's pal, the former Playmate told Jim that the spark had gone out of their relationship.

"She just looked at him and was like, 'You love me like a family member that's never going anywhere, not like a woman who you can't wait to make love to,' " recounts the insider, adding that Jim "just stared at her" for a minute, before admitting that was in love with Jenny and her son Evan as a package, but that he "couldn't get his mind right, he wanted to, but somewhere along the way, he lost it."

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The two will continue to stay committed to each other's children — Jim sees Evan every day —and even though they are "totally and 100 percent over romantically," the insider tells OK!, they'll be friends forever.

Jim and Jenny should be a lesson to others on how to end things on a good note!