There have been a handful of these stories in the last few years. The first I remember hearing about was in 2006, right before my dh and I went on our first cruise.
It happens.
I too have noticed similar stories starting around 2006. IIRC, this coincides with the release of Carl Hiaasen’s book, Skinny Dip. In it, a husband attempts to murder his wife by flinging her over a cruise ship handrail one night. It’s a wonderfully entertaining read (she survives to exact revenge), but I suggest it has given a few folks like minded ideas.