How to keep Boston Fern?

Mine do the same thing. Perhaps they prefer higher light levels than they get in my east facing windows. However, I keep reading that misting is very important when they are inside. Dry air is very hard on ferns of any type. I recommend you keep your fern away from any heating vents and mist it at least once a day.

https://m.wikihow.com/Care-for-Boston-Ferns

https://www.gardeningknowhow.com/houseplants/boston-fern/overwintering-boston-ferns.htm

I find that even though mine shed some fronds, there seem to be three new ones for every lost one. They like it cool, but need bright indirect light. Northwest exposures work in my area. Never in direct sun. Don't let them completely dry out, and misting keeps them happy. I take mine out and give them a shake off when it looks like I need to. My vacuum takes care of what I miss.

Avoid touching the leaves. The oils in our skin makes the leaves curl up and fall off

cool temps, good lighting ( not direct sun ), and LOTS of moisture ... most people use them an summer annuals because winter care is so problematic!