It can also happen to mature adults.

A different scenerio, but I've been dumped by GFs finding BFs so many times I've lost count. In addition, I've also been dumped by couples, because the "wifey" thought that I was after the "hubby."

In fact, I've lowered by expectations for friends I have up here. If I expect nothing from them, I'll never be hurt. It's just that simple.