This one has all the hallmarks of a 'family spat' spilling into public view. Micheál Martin's backers generally agree that Senator Averil Power is a very able politician with a bright future. Her departure from the party, on the highest available dudgeon, has deprived Fianna Fáil of presence in two sectors where they were already extremely shy: women and Dublin.
Senator Mary White, of Dublin South, is now the capital's only Oireachtas member of Fianna Fáil. And the party has no Oireachtas representative inside the Dublin city boundary.
Ms Power is acknowledged as well-informed, and a good media performer who understands how politics works in practice. The manner of her departure, and the timing, has left party heavy-hitters both bewildered and enraged.
Ms Power described the Fianna Fáil approach to the same-sex marriage campaign, in which she featured strongly, as "cynical and cowardly".
She said Micheál Martin was not an effective leader and the party was "not fit for government".
The resignation and castigation came scarcely 36 hours after Fianna Fáil's first victory in seven consecutive by-elections, as Bobby Aylward came home in Carlow-Kilkenny. Mr Martin was looking forward to welcoming his new TD to Leinster House today.
Mr Martin's appearance on RTE's 'News at One' yesterday, wearing his best kicking boots, was an unusual step for a party leader to take after the departure of a Seanad member. But her earlier comments had clearly stung and he made it clear that he viewed Ms Power as an epic ingrate.
Later in the afternoon, several TDs bore out Mr Martin's view that he had gone out of his way to get her support for a Seanad seat in March 2011.
Ms Power would not be in national politics at all otherwise, several TDs insisted, as they cited her disappointment that she was not the sole candidate in the new five-seat Dublin Bay North.
For the bystanders, it is clear that Mr Martin has more than his share of problems with the party which is still struggling to find where it fits in the political landscape, what it stands for and what its message is for the voters.
Mr Martin has failed to bring his Oireachtas colleagues with him, most notably in summer 2013 when the bulk of them failed to support the Government on the Protection of Life in Pregnancy Bill. The vast bulk of them voted against the measure, something Ms Power felt bracketed them with the conservative and older generation in a rapidly changing Ireland.
The Dublin Bay North situation also sums up the dilemma which is replicated elsewhere. Former junior minister Sean Haughey, son of the former Taoiseach, wants to come back and looks well-placed to take a seat. Against that, the party needs fresh faces and more women if it is to have any hope of recapturing the public confidence in bigger picture politics.
Local and personality issues also kick in. Others have expressed an interest, including Cllr Deirdre Heney, who has been active in the area for many years.
Ms Power may or may not stand as an independent. But her exit, and its timing, has clearly damaged Micheál Martin and Fianna Fáil.