Is it possible to repent after breaking a covenant with Allah to abstain from fornication, then repeatedly committing fornication with the intention of repenting later, while feeling a lack of reassurance?

Adultery is one of the gravest major sins that Allah has associated with polytheism and unlawful killing. The perpetrator of this abomination must sincerely repent to Allah. If he repents with a sincere repentance, Allah will forgive him and transform his evil deeds into good ones. If the sin is repeated, repentance is obligatory once again, and one should not despair of Allah's mercy, for the door of repentance is open. Among the things that help with repentance are: staying away from its motives and causes, avoiding its places and people, refraining from traveling to countries known for permissiveness, and accompanying righteous people.