Bathroom should certainly help with humidity. I suggest following the advice at Gardening Know How:
Boston ferns need a cool place with high humidity and indirect light. When you care for Boston fern plants indoors, it’s a good idea to provide additional humidity for them, especially in the winter. Most homes are rather dry, even more when heaters are running. For extra humidity care for Boston fern, try setting your fern’s pot on a tray of pebbles filled with water. You can also try lightly misting your fern once or twice a week to help it get the humidity it needs. Another step in how to take care of a Boston fern is to make sure that the fern’s soil remains damp. Dry soil is one of the number one reasons that Boston ferns die. Check the soil daily and make sure to give it some water if the soil feels at all dry. Because Boston ferns tend to be planted in potting mixtures that are high in peat moss, it is a good idea to soak the pot of the Boston fern once a month or so to make sure the peat moss is fully hydrated. Be sure to let it drain thoroughly after this.
Outdoors they die back to almost nothing each winter but recover every new year, so I would at least wait another year, to check this is not something seasonal, before considering discarding it.