All 4 cylinder engines in the Ford universe are either copies of or derived from Mazda MZR engines. All 6 cylinder engines are Ford products. Ford owns rights to build and use the MZR generation of engines under their Duratec brand name for global service in its vehicles since 2003. All Mazda V6's are really Ford Duratec engines.
As of 2011, Mazda discontinued development of the MZR generation of engines to be replaced by their new SkyActiv generation of engines. Ford continues to develop and manufacture variants of the Z-engine and L-engine for their Duratec and EcoBoost four-cylinder engines. The 3rd generation MX-5 is still produced with the MZR 1.8 or 2.0 engine, which may be shipped from the factory with a Ford Motor Company oil filter fitted, suggesting a shared production line.
I think Mazda divorced with Ford and is moving manufacturing back to Japan because they have determined that they no longer need V6's in their future.
Not true. The V6 engines are also Mazda design. The Duratec 30 V6 is a Mazda AJ engine, which was derived from the smaller displacement "K" family of V6 engines. The Cyclone V6's are also Mazda design by the name of "MZI"