The middle east was for generations ruthlessly but fairly peacefully controlled by cruel and bloody secular dictators - our cruel and bloody client secular dictators, who catered to us and received our money, weapons and support. Nothing happened that we didn't approve of. Saddam Hussein, Gaddafi, Assad, all of them, were all broken to our yoke. Then we got it into our high and mighty minds that we needed to get rid of these secular dictators and install democracies based on sectarian majorities, democracies which turned around and ruled tyrannically based on 1000 year old religious feuds. Result, anarchy, madness, horrific war crimes, destruction of nations, millions dead and millions more migrating to Europe. Whoops, do-over! All we need now to fix this is a time machine and the ability to put Humpty Dumpty back together again.
Except that Gaddafi never had friendly relations with the US, prompting both the US and Britain to abandon their military bases in Libya immediately after gaining power. Additionally, he nationalized Libya's newly established oil industry. By all accounts, West/Libya relations were better before Gaddafi.
Assad also wasn't brought into power by the US, although lines can be drawn back to the late 40's and early 50's where the US attempted to extend their sphere of influence to the region. In the end, the Soviet Union were the ones Assad and his regime turned to.
I of course won't deny Saddam Hussein's connection to the west up until the late 80's (I can't remember exactly when relations plummeted).
While I certainly can't and won't absolve the US and UK of their doings regarding the Middle East, I find that people tend to not extend that same level of responsibility to the various Middle Eastern countries, as if they had no independent thought or decision making skills of their own. It has become popular sport to blame the US for every single problem, often ignoring other factors or players (especially England and their part in history), and constructing wild conspiracy theories with little to no proof, just to fit their agenda. It's true that the big players in the world can and does use smaller nations as proxies or for their ressources, but let's not forget that those proxies are made up of people who are also capable of independent thought.
- - - On topic - - -
As I see it, the west had only two choices regarding Syria. We've tried intervention through supporting rebels, and it never ends well. We've tried intervening ourselves, but we fail to plan for what happens after the fighting is over. You can't take a country run by a totalitarian and turn it 100% democratic overnight, as the many reforms that need take place require the absence of the absurd levels of bureaucracy that are inherit to democracy. They also require a population that is litterate and who has access to knowledge beyond what is given to them. I don't know the education level of Syria, but I will assume (with some degree of hesitation) that it isn't near the level of western nations.
Ideally, the UN should've gone in with peace keeping forces at the very start of the conflict, removing Assad from power, and working towards establishing a new government. A combined UN peace keeping operation was, I think, the least likely to cause the population to fight back, as opposed to a full on NATO invasion. Having Russia take part was and is crucial, as it should work to ensure that the end result won't be under the direct influence of either the US, or Russia.
Given that this didn't happen, the other option was to sit back and not intervene at all. We shouldn't have supported rebel groups with arms and equipment, as we can't control what they do with them. They're not under the same scrutiny that our armies are, and, as we've come to see since, they occasionally switch sides, resulting in western supplies ending up in the hands of ISIS.
The introduction of ISIS into the theatre of operation obviously required a direct NATO and Russian intervention. Frankly, I have no idea how to effectively deal with that, as telling the various rebel groups apart from civilians, Assad forces and ISIS supporters, must be near impossible.