Is the action of a suitor who stipulated that his family not attend his wedding—fearing his mother’s rejection due to the age gap, and intending to present her with a fait accompli—religiously permissible? And what should I do in this situation?

There is no objection to a woman marrying someone younger than her. It is not obligatory for a man to seek his parents' permission for marriage, but it is an act of filial piety and kindness. If the suitor knows that his mother will approve after she learns of the marriage and that it will not lead to a severing of ties, then there is no objection. If the woman perceives the man to be righteous and she predominantly believes that his family will not disown him, then there is no objection to her acceptance. However, if there is a possibility of discord and a severing of ties, then it is not advisable to proceed with the marriage due to its negative consequences and its potential to contribute to filial disobedience towards the mother. Obedience to the mother is obligatory if she commands against marrying a specific woman, unless the man fears falling into sin if he does not marry her. If the husband resorts to stratagem and does not inform his mother, but knows that she will approve after the marriage, then there is no objection. Marriage must be witnessed and publicly announced.