Which is better: zina or secret marriage, for fear of falling into Allah's boundaries, given that the mother refuses marriage due to poor financial conditions?

The crime of zina (fornication/adultery) is one of the gravest major sins and most heinous transgressions. Allah Almighty has coupled it with polytheism (shirk) and murder, and has threatened its perpetrator with a multiplied torment on the Day of Judgment and eternal humiliation therein, except for those who repent, believe, and do righteous deeds. Islam has severely emphasized the punishment for zina, by flogging the unmarried perpetrator and stoning the married perpetrator to death, and has forbidden showing them leniency. Whoever fears falling into zina should marry, and whoever is unable to do so should fast. Secret marriage, if it does not fulfill the conditions of a valid Islamic marriage (presence of a guardian, two just witnesses, and a mahr), is zina. If these conditions are met, then the marriage is valid, even though it is the Sunnah to announce and publicize the marriage.