The deputy PM won his by-election, then two months later announced that he had impregnated a former staff member, and was leaving his wife and four daughters to raise his fresh spawn. He didn't see any reason why this should concern his electorate, and remains a member of Parliament.
In the interim, Australia held a referendum on same-sex marriage. This was demanded by the conservative faction and designed to try to nobble the "yes" vote. Turnbull gave them almost everything they wanted. It came to naught, and Australia voted in favour - 62% of votes on an 80% turnout (the vote was voluntary). Tony Abbott's electorate went Yes by 75%. It is now law.
Now. When Turnbull knifed Abbott, he cited the fact that the Libs had lost 30 Newspolls in a row. Turnbull's government has now lost 38 Newspolls in a row. The govt did poorly in July by-elections. The one thing keeping him was in the job was that they had no one better. The final straw was when he got rolled by Abbott's mob on energy policy. To try to stop a revolt, Turnbull jettisoned Australia's emissions target from the Paris Accord. It didn't work. Instead one of Abbott's acolytes, Peter Dutton, attempted the most cack-handed coup in Australia's history. On Friday he forced a leadership vote. Turnbull promptly declined to stand again. Dutton lost the vote to Turnbull's Treasurer, Scott Morrison. Abbott etc brought down the government in order to make no change to government policy whatsoever.
One final parting gift. Turnbull had earlier promised that if he lost the leadership he would resign from Parliament, as it was too destabilising to have a former PM hanging about like Banquo's ghost (I'm looking at you, Abbott). He is still promising to do so, forcing a by-election. A reminder: the government's majority in Parliament is... one seat. Vale Turnbull. As one commentator said, "He leaves a proud legacy of the banking royal commission he failed to stop, corporate tax cuts he failed to start and the National Energy Guarantee he failed to understand."
In conclusion, a bit of trivia for you: the Australian PM is the highest-paid government leader in the OECD. This is some value for money we're getting, I think you'll agree.