Is the failure to visit one's mother and fulfill her wish for marriage considered disobedience, knowing that the mother is content, and the son fears pity and disbelief due to a chronic and embarrassing illness?

If the mother is not harmed by your not visiting and does not need you, and your not visiting is not considered disobedience, especially since she is pleased with you, then the connection with the mother is not limited to visits but can be achieved by any means of communication. And if the mentioned ailment harms the woman and prevents marital relations in a befitting manner, and there is a fear of falling into adultery, then marriage is forbidden. If marriage is forbidden for the questioner, then he is not considered disobedient for abandoning it, because there is no obedience to parents in committing what is forbidden.