Infidelity is very common to married couples as well as to lovers. Keeping a strong relationship is not as easy as to breaking it. Infidelity is primarily caused by temptation, but is temptation natural? Or, is it a sign that the relationship is losing its fire? Cheaters might have different reasons why they cheat. It could be because of their partner or just simply falling out of love.
But cheaters, regardless of what reasons they have are still cheaters and will always be. Some would even say that they are repeat offenders and worst description would be habitual offenders. It is really up to the person on how many chances he can give a cheating partner, but as for many, cheaters do not deserve a second chance.