PHOEBE AND COLE
Phoebe meets Cole at the begininng of season 3. He poses as an Assistant District Attorney (A.D.A) but he is really the infamous demon, Belthazor. They date for a while then Phoebe finds out his secret. So do her sisters and they set out to vanquish him. Phoebe finds him first and because she loves him so much she let him go and lied to her sister and told them she had vanquished him. He came back later that season and helped save Phoebe's life and she and the rest of the family forgave him. Near the end of season 4 they decided to get married but what Phoebe didnt know was that Cole had become the new source. She became pregnant with an evil baby which the seer stole and implanted into herself so she could become the new source after the girls had vanquished Cole (which they did). But because Cole was half human his soul was able to hold on in another realm trying to find a way do get back to Phoebe. Somehow he obtained many demonic powers and managed to return to San Fransisco, to Phoebe. After he saves her from a witch-hunter Cole vows that he wont give up on them.Ever.