It sounds like territorial issues to me. If Faith thinks she's preggers, she could be trying to get some safe space to build a nest.

Is there any way you can give her a box or something that can be like her own "room" that she doesn't have to share with anyone?

My bun has a copy paper box with a hole cut in it so she can go inside and be alone. She likes to go in there and hide when we cook. I guess I shouldn't tease her so much about putting her in the stew pot if she's bad!