Paul W. answered 04/05/19
Dedicated to Achieving Student Success in History, Government, Culture
It's important to remember that the Crusades in the 'Holy Land' (the Levant) lasted some two-hundred years, from the 1090s to the fall of Acre in 1291. Over these two-hundred years, the boundaries of the kingdoms established by the Crusaders expanded and contracted. As these kingdoms went into decline, they lost control over territory, which meant that farms and estates were lost to settlers and the descendants of settlers. Those who were not captured by Muslim foes and sold into slavery would initially seek safety in the fortresses and walled cities still under the control of the Crusaders. Here they could decide whether or not to remain in the 'Holy Land' or to leave for some other place to live.
Ultimately, by 1291, all that remained of the Crusader States was the fortified coastal city of Acre. When the defenses of Acre were breached, the population, both defending troops and civilians, fled to the harbor. Those who could secured passage on the ships that were present. Meanwhile, the Mamluks slaughtered all they found, regardless of gender or age. Those Templars who took refuge in their bastion located on the western tip of the city were ultimately overrun and slain.
Certainly, it's possible that there were some Europeans, descendants of Crusaders, who continued to live in the 'Holy Land' after the fall of the Crusader States. Along with Muslims, the Islamic States of the Levant contained Jews and Christians within their populations, though they were decidedly 'Second-Class- Citizens'. Nevertheless, the justified hostility that the Crusaders generated in the hearts of Muslims all-to-often led to either massacres such as at Acre or enslavement. Therefore, if there were any Europeans who arrived with the Crusades and were allowed to remain unharmed, they were definitely the exception.