The temperaments tend to have different reactions to their own infidelity. Some find it easier to justify than others. Some find it easier to justify a series of short term affairs (they always return to their "true love") and others find it easier to justify a long term affair ("it's not like I'm catting around"). In America, all types can practice serial monogamy, moving from one relationship to the next but never having more than one sexual partner at a time. Sometimes a person believes that they have been forced into a marriage. In that case, they may not feel a commitment to the partner, so an affair can be justified by those of all temperaments.

Guardians generally make faithful mates. Usually if they engage in an affair, they will either soon stop it and go back to their mate or they will work to make an end to the first relationship in favor of the second. Guardians can have long term affairs if the first relationship is needed for status, power, or the sake of the children. It is fairly rare for Guardians to have a series of affairs. To do that, they have to somehow talk themselves out of any sexual commitment to their partner.

Artisans are the most likely of the temperaments to engage in infidelity with multiple partners. That said, most don't. The habitual adulterers do it for the thrill of the chase and the victory of winning the other person. Artisans tend to have the highest sex drive. If their partner can't or won't perform, they may look for a purely physical relationship. They are also the most likely to use an affair as a weapon. If their partner wrongs them, they may choose this nuclear option.

Rationals tend to be faithful, with Masterminds (INTJ) the most likely and Inventors (ENTP) the least likely. As a rule, Rationals have a more manageable sex drive than other temperaments. Sex is still very important to them, but usually not as all-consuming except during the teen years. Rationals are the most likely (along with Promoter and Crafter Artisans) to separate sex and love. When they do that, they may have little trouble justifying an affair. Inventors sometimes act like Artisans, going for the adrenaline high of conquest.

Most Idealists have a difficult time with sustained infidelity. They have a high need to be true to themselves, and they tend to have a romantic view of love. Infidelity is inconsistent with both of these. If you have made a commitment to a person, being unfaithful to them means being untrue to yourself. Unfaithfulness and romantic love just don't mix. Affairs tend to be short-lived because guilt kicks in fairly soon.