2002 - Enourmous pressure on Turkey to open it's territory for US's attack on Iraq. Turkey was selected as Norther Front. 62.000 US troops were supposed to march through Turkey.
2003 - Neo-Con's fabricate a war.
2003 - 2007 PKK attacks on Turkey rise exponentially
Neo-Cons like Wolfowitz demand apology from Turkey.
Wolfowitz
'Let's have a Turkey that steps up and says: 'We made a mistake. We should have known how bad things were in Iraq, but we know now. Let's figure out how we can be as helpful as possible to the Americans,
AFTEREFFECTS: DIPLOMACY; Turkey Rejects Criticism by U.S. Official Over Iraq - New York Times
With such mindset it's no wonder the USA armed the PKK as punishment against Turkey for not participating in a fabricated war.
Attacks of PKK rise, from Washington come constantly vioces, that Turkey has no business in N-Iraq - not even to attack the PKK bases.
In November 2007, then Foreign Minister Gül (now President) travels to White House whilst the 2nd Army is amassed on Iraq-Turkish border. Relations stand at total collapse.
At that November 2007 meeting, a comprimise is reached: US planes from N. Iraq withdraw so Turkish jets can operate there. The US from this point on submits 'actionable intelligence' to Turkey. And Turkey promises to launch only a small-scale military operation into N. Iraq.
That Operation happens in the Winter, where the Army would kill 724 from the estimated 4.000 terrorists operating out of N. Iraq:
2008 Turkish incursion into northern Iraq - Wikipedia, the free encyclopedia
Independently, but around same time, it becomes evident, that Turkey won't join EU despite holding accession talks with the EU. Some serious shit in Turkey's neighbourhood is going on - against the interests of Turkey. Turkey decides to counter these foreign-designs on her own borders and in her own neighbourhood.
So, Turkey begins to project greater Influence over the area.
In that process Israel is turning out to become another point of friction between USA and Turkey.
It's beyond any repair (USA-Turkey), due to geo-political conditions (which are changing fast) USA and Turkey still co-operate on bigger issues or macro-level.
Together with Lobby-Games in Washington from Israelis and Armenians, who produce Anti-Turkish resolutions or hinder Ambassadorial nominations to Turkey (No US Ambassador in Turkey since summer 2010), there is nothing left of nostalgia of old times. We are just waiting for multi-polar world order to emerge to downgrade the quality of our relationships with USA significantly. In that multi-polar world Turkey envisions herself to be the dominant country of the West-Asia.
Washington is infected by one of those competitors (Israel), so there is no hope for US-Turkish relations in the long-run. Simple as that.
The breaking-point was Iraq-War and all it brought. Still, with European allies, the USA will do honey-moon again, given that you do not elect some asshole Neo-Cons again. But with Turkey it's over.