op this pattern plays out over and over again.

one spouse/partner etc has no symptoms and the other gets hit hard or has some symptoms.

Your fiance is the one who gave it to you. She was minimally exposed when she was briefly exposed to it. So she has no or very very symptoms.

You on the other hand were around that virus shedding lady for days, being assaulted non-stop by her shedding, so your exposure to the virus was a lot higher, meaning you are way more likely to have a worse course of the illness.