Is forgetting a sin—close to a major one—in order to avoid feeling its pleasure and longing for it, considered apathy and belittling the sin?

The effect of sin varies among individuals. It may transform into a blessing for those who follow it with repentance and submission to Allah. Forgetting the sin is commendable to distance oneself from its ill effects and from being led astray by Satan, and it is not considered belittling the sin. However, for those whom sin leads to brokenness and increased humility, it is better not to forget the sin, so they may remain steadfast in their repentance.