https://www.homedepot.com/p/Owens-Corning-R13-Thermafiber-Fire-and-Sound-Guard-Plus-Mineral-Wool-Insulation-Batt-15-in-x-47-in-1310109/319880476

This is the kind of thing I would suggest, it's designed to be soundproofing, fire retardant home insulation. This is literally the exact thing you would put in-between your joists before drywall if you were trying to insulate an interior wall for sound.

There's a product called green fiber that is a blown-in cellulose insulation that's been treated with fire retardant you could use if the walls have already been drywalled, I've used that in all of the interior walls of my home when I was remodeling to try and deaden sound and have added privacy throughout the home. My basement, which I turned into a mother-in-law apartment, is so private I can't hear my basement neighbor when they have their video games blasting through a surround sound stereo set with a subwoofer. I can feel the floor shake but, unless I am standing right next to a vent, I can't hear anything.

I stopped being so upset by it once I started examining social systems and propaganda. If you've been conditioned your whole life to think of women as weaker and smaller and someone to be protected to maintain your "manly state", someone who doesn't fit that mold is a threat to your subconscious sense of self worth. Same for women who don't want to date shorter men, "if I'm not the property of someone who's the biggest and the strongest, I'm worth less to this society."
'Society' thinks men who are smaller than their woman are weak, and that the woman must be defective or she'd be with someone who 'fits' better. They're dead wrong, but that's the unexamined subconscious judgement that our society has conditioned into people. It's easy to be less upset with individual people when you realize they just haven't had the space to examine the abusive systems they're forced to exist within.

Thanks!