Can straitened provisions and unfacilitated affairs be a punishment from Allah for the sin of zina (fornication/adultery)? And does Allah forgive this sin through seeking forgiveness (Istighfar) and acts of worship? And what is the way to expiate this sin and overcome its effects? And is it obligatory to disclose this sin to a future wife?

Sins open the doors to evil, and in this world, they cause straitened livelihoods, anxiety, and sleeplessness. The blocking of the doors of provision is caused by sins, for "Indeed, a man is deprived of provision by a sin he commits." One must praise Allah for His concealment and for not exposing them, and blame oneself, not Allah. You have done well by seeking what is lawful. Allah the Almighty says: (And marry the unmarried among you and the righteous among your male slaves and female slaves. If they should be poor, Allah will enrich them from His bounty). And, "There are three whom Allah is obligated to help," and among them, he mentioned "the one who marries, seeking chastity." Do not tell anyone about what you did previously, for repentance wipes out what came before it. Your sincere return to Allah and your devotion are two reasons for forgiveness. Do not despair of Allah's mercy: (Say, "O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful"). And 'Umrah may be an expiation for what has passed.