Some people have a low EI
There are several different types of intelligence in the world, including emotional intelligence, which is vital for sustaining a happy, healthy relationship with another person. According to McRitchie, people with low emotional intelligence might be more inclined to cheating.
“Emotional intimacy or intelligence is essential for a healthy relationship – and whilst it cannot always guarantee fidelity – it does stand a relationship in good stead. How often have we heard [someone] say ‘[they] just don’t understand me’? It sounds like a cliché – but often it has its base in the truth; the person doing the cheating feels unheard, or unseen – but they are perhaps not communicating in the way they should and so of course are not understood.”