Ishita's permanent place is Couch!
She can use bed when:
1) Ruhi on bed
2) Raman try to consumate.
I think after consummation, she has to go back the couch. Then give birth to baby in hospital BED. After that she will come back to her PLACE couch!!!! but she can use bed whenever others need her as per conditions!!!
PS: Sorry, If I am rude, pls Report