My 3 year old fiddleleaf fig plant has been doing very well since I got it. Then about two months ago, this happened (see attached photos). It has dropped about half of its leaves. I water it when it is not quite dry and it sits in a filtered eastern window.
Any ideas on what is going on? Please help!

It may be that it got too dry, the lower foliage was not able to get enough light, normal senescence of older foliage, or the rootball has run out of room to keep growing and the plant has reached its max amount of foliage that it can support, dropping older leaves that are no longer as productive as the new ones. Or some combo of the above.