Julian and Shannen Doherty did date for a while, I believe it was some time during the filming of season three and perhaps for sometime after. I'm not exactly sure on the when, but I know it happened.
Just do a google images search of "Julian Mcmahon Shannen Doherty" for proof. Here's the results:
Image results Julian & ShannenThey did both star in a movie called 'Another Day' in which their characters were in love, and a few of the images are from that. But some are from real life: the ones on the beach, etc.