I'm so sorry for your loss.. How does Star seem to be doing? Some are very unhappy without other rats, but some are just fine. If she's ok then just extra time out with you might be enough for her.... With your hubby's asthma do you have her on the bed or your couch? You can make outings more fun by adding boxes or paper bags.... Maybe you could add something to her cage like a new hideyhouse or reconfigure sometimes to make exploring more fun.... Do you take her fore shoulder rides? If not, maybe you could train her with treats there to enjoy it and take her on explores around your place and let her sit there while you are at computer....
My little guy is alone too. My only bare floor is in the kitchen so in the mornings I block the doorway with a large piece of cardboard (from an opened cardboard box) and let him run around there while I have coffee & do work at the kitchen table, I have a stool beside the chair so he can get up and down with me when he wants to.