Does death come in threes?

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I've often heard that death comes in threes and in the past its proven to be true. Why is that? I've now been close to 14 deaths in the past 3yrs. That just seems unreal to me. Last Monday, my FIL didn't wake up. Today my dad's girlfriend. I'm trying not to worry but my sister and I can't locate my dad. Where ever he is, he's chosen to grieve alone. I didn't even find out until my MIL found out while she was out running errands and called me. Has anyone else experienced this "death in threes" scenario??