Hi and welcome, so sorry to hear your sad news

We had to make the same decision about our old Dalmation last year. He was pts at home and we let Zeus spend some time with him afterwards so he would hopefully realise that he had passed away. He was very attached to Jake and he grieved too.
They had always slept seperately though as it had taken Jake a while to accept another dog in the house, Zeus would check every room downstairs when he got up and then throw himself down in a corner looking very sorry for himself. He went off his food too but he had always been quite a finicky eater. We gave him loads of extra attention, love and prolonged play sessions to try to cheer him up. A few weeks on he was still depressed and was losing weight so we decided to find him a new friend. Maisy was full on from the day we got her, she didn't give him a minutes peace, he soon got back to his old happy self.
As you still have 2 dogs, I would give them both lots of attention, maybe she's confused and thinks your old male is still in the house, she will still be able to smell his scent around. Or maybe she is unsettled because of the hierarchy of the pack changing. I can understand you not wanting to change her routine, i'm too soft (both of mine sleep in our room) and would let them sleep in the bedroom or put a childgate on the bedroom door and allow them to roam free for a while till things settle down and improve.
I don't know what else to suggest

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Regards
Bet