How common is a preference for a partner’s armpit scent? (Non-sexual, comforting)

I’m posting here because it’s really hard to find clear stats or open discussions about this, mostly because people aren't always comfortable talking about body scent preferences.
My partner is extremely attracted to my natural armpit smell. What’s interesting is that it’s not even in an explicitly sexual way, he just genuinely enjoys the scent, and he says it calms him down and soothes him when he’s stressed or relaxing.
At first, I found it a bit unusual, and I’m curious how common this actually is. Is this a recognized thing (like a biological/pheromone reaction or a sensory comfort item), or is it considered a niche attraction?