Is a young man suffering from social anxiety considered sinful for refraining from visiting relatives and being unable to help his parents except in specific situations?

If refraining from assisting one's parent in what is necessary, or refraining from maintaining kinship ties without a legitimate Shar'i excuse, then that is a sin. This is because Allah has enjoined honoring parents and maintaining kinship ties. It is not permissible to shirk (definition) religious and social duties without an acceptable excuse. It is advised to strengthen one's character, be mindful of Allah's companionship, rely on Him, and confront fearful situations such as assisting one's parent, visiting relatives, and praying in the mosque. These matters strengthen one's character, remove fear, and break psychological barriers. And recall the Prophet's (peace and blessings be upon him) saying: "A strong believer is better and more beloved to Allah than a weak believer, and there is good in both. Be keen on what benefits you, seek help from Allah, and do not be helpless. If something befalls you, do not say, 'If only I had done such and such,' but rather say, 'Qaddar Allahu wa ma sha'a fa'al (Allah has decreed and what He willed has happened),' for 'if only' opens the door to the work of Satan."