The French arrogance destroyed the FCAS project they had with the Germans. The French have very high opinions of themselves.
To some extent, the French are justified in having a high opinion of themselves. They have maintained a mostly sovereign military-industrial design and manufacturing base, whereas Germany and other European nations have not. Given the present political circumstances, Paris could be forgiven for being rather smug about possessing Europe's only truly sovereign nuclear deterrent, the product of decades of often contentious investment. When these same disputes arose under FEFA in the early 1980s, France parted ways with the other project members and went on to develop the Rafale by themselves, while the UK, (West) Germany, Italy and Spain continued their collaboration to produce the Typhoon. From a quick Google search, it isn't clear to me which of the two aircraft actually has more orders on the books, but certainly Rafale cannot be dismissed as a failure.
That France remains committed to maintaining a sovereign air combat capability does not mean that shared development is impossible. Given the cost of developing a new platform, and the challenging economies of scale in producing and maintaining it, Paris should be highly motivated to welcome development partners insofar as is practical and insofar as they can be accommodated. But it does mean that
very careful consideration needs to be given by all prospective partners as to the compatibility of operational requirements (e.g. the design implications of the French requirement for carrier compatibility), industrial requirements, envisaged project timelines and budgetary contributions, and export philosophies.
The finer details of the disputes have largely been denied to us. The French may simply be duplicitous bastards. It's equally plausible that the Germans, having been progressively roused from their slumber these past few years, are attempting to revise terms of cooperation that were once but are no longer acceptable. At the end of the day, France
will develop a successor to Rafale, and Germany
will find a successor to Typhoon. Whether those items occur under FCAS or some other acronym and set of partnerships doesn't really matter.
French engines are not even as good as the F414 in reality. See how bad the M88 on rafales are.
M88 is not "bad". It is a smaller and lighter engine than either F414 or EJ200 and is optimised for difference performance parameters.