Here's what actually happened:
* Shannen Doherty left Charmed after season 3 due to creative differences and on-set tensions with the producers and her co-stars.
* Alyssa Milano stayed on for the remaining 4 seasons.
There were reports of tension between Shannen and Alyssa during the first three seasons, but the exact nature of their relationship is unclear. Some sources suggest there was a personal rivalry, while others point to differences in their work ethics or creative visions for the show.
It's important to note that Shannen Doherty's departure from Charmed was not directly caused by conflict with Alyssa Milano. The showrunners ultimately made the decision to let her go.