Why can't I get Rested or Well Rested?

Question

I sleep in rented beds and my bed in Jorrvaskr (with the Companions) and no matter how long I sleep I don't get the notification that I'm rested or well rested anymore.

I've looked at my active effects to check for Lycanthropy or Vampirism and all I have are positive effects.

I have slept in rented beds immediately after receiving blessings and having all diseases cured at the shrine of Mara.

What are other reasons I might not be able to get rested or well rested?

Answer

You've got the Lover's Stone active.

It doesn't stack with the Rested / Well Rested / Lover's Comfort effects.

Check more discussion of this question.