How do I keep my fern from drying out and dropping so many leaves?

https://www.gardeningknowhow.com/houseplants/boston-fern/boston-fern-leaf-drop.htm

Misting it with water everyday will help. They do not do well in dry heat.

It may be getting too much sunshine. Most ferns in the woods and rainforests are sheltered in shadows by tall trees and other foliage. And, yes, dry heat is the worst. 😇

Put it in your bathroom. The steam from showers will help.

Get a moisture meter since it is in the dry heat in the house now. It will help you know when to water your fern. Misting it every day will also help.

Water it well. I put mine in the shower and give it a good soaking, then mist the leaves every couple of days. It's going to drop a few leaves anyway. I take mine outside and give it a good shake, then bring it back in. You will see new greenery start to sprout, but it really won't go full until you put it back outside in the spring.