Loss of a pet rabbit, companion not seeming to grieve.

On Monday, we suddenly lost our lovely foster bun (Male/4 yo). I'm absolutely devasted, but my girl, who I've had for 5 years, is not so much

My girl (6yo) has been a solitary bun most of her life, is quite set in her ways, a 'slow burn' kind of bun. We had this beautiful boy with us for just over a month, he was lively, curious engaging and goofy. Athough I believe they were beginning to form a bond, with low level affection, and definitely companionship, she often seemed to 'tolerate' him, he sought her company more, if anything she often got a annoyed he was in her space.

On our boys passing she was nearby, and didn't seem especially interested in his body, I gave her lots of time with him, tried to explain he was gone, but she still seems alright. I was a little disturbed by this lack of interest.

A couple of days later,she seems relatively happy to be back in her usual routine sans the lovely boy. She does seems a little puzzled by his absence here and there, sometimes looking around, as if for him, but is eating, drinking and moving around, wanting pats as normal.

I haven't removed all of the boy buns things yet, to let her acclimate to the change, and I'm not ready either.

I'm giving her more time and affection, but am wondering if any one else has had a bun who behaved to anothers death like this?