Uhm I guess since this is not an omegaverse setting, just based on the concept of “animals”, pheromones is not exactly a concious superpower concept controllable thing (detectable tho) and may just stick on you from places you’ve been to or other people you’ve met. That’s why since MC bumped from wolf-kun it kind of unconciously picked up friend-kun’s scent without knowing even though they just met a few couple times. Cuz the wolf-kun friend is already very lovey dovey with their mate, loprabbit-kun.
Same concept of how even snubby cats are all over you when you’ve been outside. Or some dogs peeing on your shoes or bags after an outside trip. Like “marking you” with their scent cuz you pick up unfamiliar scents from your time outside.

Why were they scenting each other I’m not sure that was answered