Chihuahuas aren’t particularly more fragile than other dogs, it’s all relative to scale. Obviously they're smaller, but jumping off a couch isn’t going to break their bones 🙄 and as for cold...this seems to be an awfully fluffy chihuahua, so it’s probably more cold resistant too.
How does the MC think girls act? Squealing, getting embarrassed over a guy, hugging a body pillow of a male character...she’s pretty girly.