Turkey has to do this.
The PKK and its affiliates have been at war with Turkey since 1978.
The PKK and its affiliates are a threat to Turkey geostrategically because the territory they've gained during their campaign in Syria cuts Turkey off from Iraq and Syria, plus there are insurgencies all throughout the Eastern part of Turkey. With this new gained territory Turkeys regional Hegemony has been called into question which is unacceptable because it must check Russia, Israel, and Iran.
Furthermore, given the momentum, publicity, and experience the Kurds have gained the last few years makes them a threat to the Turkish State itself. Do you know what the Kurds demand? They demand a separate state from Turkey, Iraq, and Syria. With the Kurds newly established territory and hegemony they now have the capacity to act like they are a state even if not recognized. The danger this poses to Turkey cannot be understated.
This is the opposite of betrayal.
Turkey is a NATO member and safeguards the region - at the end of 2016 Turkey secured its border and took in the most refugees of any country - . Turkey also houses U.S. nuclear systems under the direction of NATO policy
A betrayal would be funding, arming, and supporting a rebel group against a NATO member whom you actually formerly have an alliance with. I recall everyone freaking out because Trump wanted NATO members to pay more per GDP and how such rhetoric is dangerous.
In this case, standing with the Kurds threatens further regional stability, NATO, and the world.
No offence but the Kurds are not worth it especially given we owe them nothing and never formerly established a relationship on paper.
As the old saying goes, the enemy of my enemy is my friend.
KPP was an enemy of ISIL hence they were our friend.