To be honest what happened in Italy isn't really ideal.
In the UK the last election was hung parliament and incumbent PM gets the first chance to form government during hung parliament which was Theresa May. The party she was leader won the most seats and the most votes and had the only possible arithmetic since it was only a couple off a majority anyway. When she resigned as leader of her party, it did not change the fact her party had the only workable majority. Hence, when Boris Johnson was elected new leader of his party he also became PM. If Italy was the UK, then Luigi Di Maio would be PM, what happened in Italy is the equivalent of somebody random like Ian Paisley Jr becoming PM becoming PM at last election.
What you are saying is not logical, on one hand you say many countries brake the rules but on the other you say the UK has apparently is unrealistic to try to get changes it wants by having the decency to ask. Am I missing something?
When the UK joined in 1973 it was a trade block called the 'European Economic Community' which had the aim of economic integration, including a common market and customs union. In the last couple of decades it morphed into completely different post-Maastricht treaty called the 'European Union' as the new title suggests a supernational union. There was no Euro when UK joined; there was no Common Foreign and Security, Policy; there was no three pillars of the European Union; there was no President of the European Council. Nobody asked the people in UK if it wanted these things, the EU just moved the goalposts, and when the people of the UK were asked of the opinion of the EU during the referendum it said no. Which isn't a surprise considering David Cameron told the country to vote based on the outcome of his botched renegotiation which he tried to sell as a success. The truth is the EU could have got the UK to if it really wanted to but it didn't So you are probably right when you say "Divorce" is the best option for both sides".
I will tell you a little story
What happened in Italy evidently wasn't ideal from democratic point of view but the only way those two parties managed to make a coalition government was that neither has the top. However since both are anti-establishment they did this compromise, especially since their voters liked the idea. Since with this they got the government that generally fights globalism, lack of welfare and in general doctrines of neo liberal global capitalism. I said what I said exactly because democratic rules aren't 100% strict when you take a look at the big picture. Yes, in UK this would go differently but there is no need that everything goes as it would in UK. So as long as the voters aren't rising the mass "counter-revolution" due to very low approval you are in the realm of democracy.
When you take a look across the block the trends are clearly to move away from free trade and more towards welfare and perhaps nationalism. Mainstream politics collapsed in Italy as well as France. Spain booted right wing out of the office and placed socio-democrats in there, Poland's nationalists with pride are showing their welfare programs, Merkel is clearly weakened, Hungary is expanding their government and they nationalized the retirement system, Greece got one very developed far left from modern dynamics ..... etc. Therefore it is to expect that Cameron will be unsuccessful in what he wanted out of EU. However all of this has the concrete source behind it, which I will explain mostly through my country.
A few days ago I was in an ex war zone in my own country that covers about 40% of it. However situation there isn't good, there are houses in ruins, houses that look as Swiss cheese due to dozens of bullet holes, economy is weak and still partially in ruins, population is something like half of what it was 30 years ago ... the damage is so great that it isn't realistic that this will be fixed through simple market dynamic. In a way this is why western military interventions tend to fail, since unregulated capitalism has no real answer for war zones. Especially if local population never lived in western capitalism, what is the case in my country. To be fully honest to me unregulated Capitalism makes no sense as an idea because if we are all going to fight each other in economic sense then we may as well do it like "real men". Why spend years or even decades of hard work in trying to bankrupt all your competition when you can just take it all by force over a weekend ? I grew up in such environment/climate and to me the endless market struggles are pointless and I can't go back to some more innocent picture of the world. Therefore if you have the energy it is better that you invest it in something cooperative or constrictive than a pure pursuit of the money.
The same is with my parents whose life was nuked first with decades of Communism and then once again with the biggest war in Europe during the second half of 20th century, plus the aftermath that still isn't over. What is the point of forcing people like that to compete with someone in Asia that works for 100$ or some English speaking person that has 20 times more money that them ? That is dumb as it is unemphatic, while feeding them with toxic imported chicken surely wouldn't make it right. After everything they should get at lest some decency before they die, since otherwise they will end just as my grandparents. Which went through all of that plus WW2 in their backyard and dictatorship before it. Plus what is even the point of placing everything on market when my region can still once again go up in flames since the underlying problems weren't solved. Until the 90s we were unified country/market and that still went up in flames, just as federation before it. So I refuse the idea that trade will fix everything. I am a young person but I went through 2 currency collapses and therefore for me it is hard to see money as something with absolute and permanent value, while my grandfather went though 6 currencies while living on the same piece of land his whole life. In other words with constant currency restarts the economic conservatism makes no sense at all. What was one of the idea behind the Euro as a currency, if you share the currency that will reduce chance of war. Which we had so many on this continent that just naming all them is science for itself and that is exactly so many white people live overseas.
Also to be honest when I take a look at UK politicians they all strike me as a career politicians that never had their ass kicked for real. While here political spectrum is mostly made of people that were locked up, tortured and beaten for years and decades because of their political ideas. Or at least they saw this happen around them or to their friends or mentors. However people that went through something like this surely wouldn't put too much emphasis on money since they would have other concerns. Actually not only that we still didn't find all the victim remains of the dictatorships and wars, we didn't even find all ministers that were "removed" due to their way of thinking. It took as many decades just to make some politicians that are young enough that they aren't too emotionally involved in this. However they have serious popularity problems, if anything because "this isn't what the founding fathers wanted". Also it is important to mention that for half a century we had Marxism as a school subject, what means that everyone above 40 got a decent education in it and that includes 90% of politicians. It doesn't even matter what you really think about the subject but such education will leave a mark on decision making.
As a matter of fact when we joined EU not so long ago one of the biggest hopes was exactly that EU politics will transform our national one, which is so stuck in the past and corruption problems. To some degree this is even working but EU too quickly took too many post Communist countries and now it is being overwhelmed. The union is doing this from the start but it seems that it took too large chunk and without detailed plans how to stabilize the whole thing. Since the expansion was mostly done for economic reasons and now you have plenty of nations that feel colonized, to the point that they may even blow up the union. From what I understand Ursula came into picture exactly because the East didn't trust the original spitzenkandidat and that opened the back room talks to the degree it was done, especially since some other spitzenkandidats were even less acceptable. Therefore there had to be a compromise, so that we don't blow up the union. Some democracy was traded for stability but I find that reasonable.
However I am telling you all of this due to concrete reasoning: Some don't want to admit this but EU at this point is basically "counseling group for those from violent and dysfunctional families". Since from the start it is spreading into countries that are ex dictatorships in order to to try to fix the situation there. Until 70s almost all of the continent was covered with dictatorships, or at least ex WW2 dictatorships and ruins. In other words almost all EU members had long term dictatorship in 20th century and the primary goal of EU is just to keep the peace and repair the damage. This is exactly why we see huge backlash against everyone that is for more capitalistic neo-liberal politics, since trade isn't what EU should be all about, because trade and money divide but definition. However if you don't share our totalitarian history and problems that came out of it you don't understand what is really going on here. You can criticize the whole group as much as you like but that wouldn't achieve anything of substance. Therefore if you are going to threat abuse support group as a business meeting you are evidently in the wrong place.