When Loki falls from Asgard to Midgard, he ends in Torchwood where he meets Rose Tyler. She automatically sees something is off with the way he looks at her. It takes her weeks before she finally finds the nerve to ask him about it. So he tells her about Sigyn, his lost wife whom Rose looks perfectly alike.
"She was more beautiful than the sun, more refined than the moon. Legends say the stars were jealous of the light in her eyes. There was more gold in her hair than there will ever be in the palace of Asgard. Her heart was more gentle than all the others Asgardians combined. She could have chosen any noble warrior. Any duke or any count, and yet she decided to stay with me. I could live a thousand more lives and never deserve her."
"She sounds… perfect."