I spent a couple years in my own thoughts without talking much about Mom either when I thought it would just change the mood. I might sulk or go cry alone, but I didn't know if anyone else did. Dad actually mentioned it to me once, when he and I were in a rare moment, that he wondered why we never talked about ~it~. It opened the door and now we do. People are too shy and maybe feel to inarticulate to bring up bad things and so it remains the elephant in the room everyone walks around without acknowledging. I would guess they are thinking about it too, more than you think, and feel the same reluctance you do. Personally, I think it is not such a bad thing to bring her up, if it sombers the mood, that's OK... That is not always a bad thing.
The guys are prolly thinking about it too. But don't know what to say about their thoughts either.
In time and ~with practice~ including her in conversation, you can all talk better about her more often. For me now, Mom (and my grandparents) are beloved conversation... "Remember when this happened", or "Mom always did that" or "This part of this movie reminds me of Mom". There isn't a pregnant silence now when she comes up... but smiles, wistful ones, or sighs, but the best kind.... The kind when you remember to remember.
You may have noticed that I cannot seem to help talking about my Grama. I notice when I go home though that I get those pregnant silences when I mention her. I always feel like I shouldn't have mentioned her but it just comes natural to me. Right out of my mouth without thinking. I think I make the others uncomfortable though.