PIT (Parental Investment Theory) also explains patterns of sexual jealousy. Males are more likely to show a stress response when imagining their partners showing sexual infidelity (having sexual relations with someone else), and women showed more stress when imagining their partner being emotionally unfaithful (being in love with another woman). PIT explains this, as woman's sexual infidelity decreases the male's paternal certainty, thus he will show more stress due to fear of cuckoldry. On the other hand, the woman fears losing the resources her partner provides. If her partner has an emotional attachment to another female it's likely that he won't invest into their offspring as much, thus a greater stress response is shown in this circumstance.
