Revenge is now the second biggest reason for infidelity, topped only by “being in a sexless relationship” — the excuse given by more than a third of those polled.

Feeling neglected was the third most common reason, a major newspaper reported.

An extra-marital affairs website found women are more likely to have a revenge fling, with 57 percent admitting to it against 43 percent of men.

The peak age is 25 to 34, with older couples more forgiving of infidelity.