I'm a bit confused about what the 'sleeping in your bed' really means.
Does it mean sex? Does it mean sleeping in the same bed?
Which brings me to another question. Is she having sex with C every single time she sleeps in his bed? If yes - then I understand your frustration and don't have much advice. If no - then I think it's worth looking at what the bed means, and what the 'sleeping together' means, for all of those concerned.
It could be she's not feeling like sex - grief can do that to a person - and that she feels pressured to have sex with you when sleeping in your room. Maybe she doesn't feel as pressured about this when sharing a bed with C. ?
Maybe you could be really explicit about this? Tell her you want to spend quality, intimate time with her, hold her when she wakes up in the night and is feeling sad, talk in the dark, just BE together without the sex part? (Which is why I would probably not use the word 'desire' so much.)
It doesn't sound ike she's emotionally shutting you out. Good luck with the talk.
early forties, straight.
the guys: Ren - husband; Curlz - bf of 2 years, Brig - bf of 7 months; Knight - non-sexual bf; MrBrown - it's complicated
Ren's girls: Lou - gf of 2 years, Liz - very new gf