What is the ruling of the Shari'ah on parents delaying the marriage of their son who resides in Europe, despite his fear for himself of falling into immorality?

Filial piety and obedience to parents in what is good are among the greatest acts of closeness to Allah. However, the validity of a son's marriage does not depend on their approval. If a young man fears falling into sin and is capable of marriage, he must hasten to it, and he is not obligated to obey his parents in delaying or abandoning it, especially if he resides in non-Muslim lands. The Prophet, peace and blessings be upon him, encouraged youth to marry if they were able to afford it.