The concept of heaven doesn't fit reality.

Humans are "difference engines" -- meaning, that we can't really sense absolutes, we can only sense differences.

If your day is "perfect" every day, then soon you would adapt such that a hangnail is a horrible day, a disaster. Similarly, if every day you spend scrounging in garbage for food, then finding half a muffin that is not moldy is a banner day.

If heaven consists of no suffering and every day being perfect, how long until the slightest deviation constitutes wretchedness?

Heaven is like infinity. An idea that can never be reached -- even in heaven.