I can see it happen. and I can imagine that the husband noticed it sooner than later but still just go with it because it might have become an activity to fondly remember his wife.

Drip trays maybe

I’ve got a brown thumb, but my wife’s is green and I’m pretty sure she tells me to water until I see water come out the bottom. Usually fake plants are in a roughly porous base, so it would absorb a bit of water which would eventually evaporate and maintain the illusion.