There were many triggers for this in the past five years and many in Sena feel what happened was "inevitable".
For starters, in 2014, the BJP, led by Chief Minister Devendra Fadnavis, managed to form a minority government with the support of the Nationalist Congress Party (NCP) to clear the floor test. The Sena opted to sit in the Opposition for around a month, and then walked lock, stock and barrel into the treasury benches, leaving even the NCP dazed.
At that time, the Sena had repeatedly insisted on getting the Deputy Chief Minister's post and a few plum ministries, including Home, Urban Development, Rural Development etc., but were continuously spurned by Fadnavis.
Peeved by the insult, the Sena kept quiet but mentally resolved: "They deny us the Deputy CM's post now (2014), we will take the CM's post next time (2019)."
Given the state of the Opposition in the last Lok Sabha elections, the Sena initially grumbled, but later fell in line after BJP President Amit Shah called on Sena chief Uddhav Thackeray at his residence 'Matoshri' to seal an alliance deal and it paid off handsomely.
In 2019, apparently buoyed by the recent Lok Sabha successes, a confident Fadnavis asserted at the fag-end of the last Assembly session: "Mee punha yaeen, Mee punha yaeen, Mee punha yaeen! (I will return)". The Sena listened silently, though some leaders may have sniggered privately and thought "We will see how!"
Then came the Assembly elections in which the Sena reluctantly agreed to just 124 seats against the BJP and other allies contesting 162 seats in the 288-member House.
Despite the pre-poll alliances, the election threw up a fractured mandate and the Sena took full advantage of it with party President Uddhav Thackeray proclaiming that "all options are open before us", leaving the BJP shell-shocked. The subsequent political developments proved that the unexpected Sena threat was real.
At the same time, Thackeray invoked an old promise made by the BJP, Shah and Fadnavis on equitable sharing of power in Maharashtra, including the post of Chief Minister and ministerial portfolios.
Thackeray and his trusted Sena MP Sanjay Raut kept harping on this daily since the election results came out on October 24, making the BJP jittery.
A worried Fadnavis met Shah in New Delhi and later the Rashtriya Swayamsevak Sangh (RSS) top brass in Nagpur with the latter advising restraint, and possibly, even a stint in the opposition benches. There were even talks of replacing Fadnavis with Union Transport Minister Nitin Gadkari, but he suddenly opted out for reasons not known.
Though Fadnavis went into a low-profile mode after the RSS meeting, the party continued to drum up support virtually till Saturday and asserted that the BJP would form the government under him. However, former minister Sudhir Mungantiwar also put a rider saying the BJP would not form a "minority government", keeping the door ajar for Sena.
Meanwhile, there were reports that NCP President Sharad Pawar was inclined to prop up a Sena-led government though Congress President Sonia Gandhi was appalled by the idea. Both have privately and publicly stated that for this miracle to happen, the Sena would first have to quit the ruling BJP-led NDA government in the Centre where it has one Cabinet minister.
At his press conference on Friday, Fadnavis, however, reiterated that there was "no understanding on the sharing the post of Chief Minister at any time", and said that he and Gadkari had confirmed the same with Shah.
Stung by the second attempt to virtually portray him as a "fibber", Thackeray hit back a couple of hours later, terming the BJP as a "party of liars" and vowed that he would not talk to them.
Amidst talks of possible 'horse-trading', the Sena herded its MLAs to a modest hotel in Bandra West, and later to the five-star hotel, The Retreat, while the Congress shifted its legislators to Jaipur with the NCP also keeping a close watch on its elected representatives.
Late on Saturday, Governor B.S. Koshyari invited the BJP to indicate its willingness and ability to form the government. But there was little joy in the BJP, which still hoped for a change of heart by its estranged ally, which never happened.
A Sena source said that as late as Sunday afternoon, word had gone to the BJP that if it wanted to save its face, then it should "change the face" (someone else instead of Fadnavis).
With both allies not even on basic "talking terms", a dejected BJP finally announced that it is "unable to form the government despite its pre-poll alliance having a clear public mandate" and blamed the Sena for "insulting" the mandate.
Now, all eyes will be on the next moves of the Governor, Thackeray, Pawar and Sonia Gandhi, which will decide the contours of the next government in the country's second biggest state, both by population and politically, in terms of the number of MPs it sends to Lok Sabha.
(Quaid Najmi can be contacted at q.najmi@.in)
( With inputs from IANS )