I don't really like to frame the difference as some people having strong character and others having weak character. I think that is too blunt an instrument for what is actually going on psychologically.
What interests me much more is the role of shame.
Brené Brown has researched and presented talks around shame, including work involving incarcerated populations, and one of the things she emphasizes is that shame is strongly associated with a number of destructive behaviors. The basic idea, paraphrasing her, is that when a person's identity is organized around a deep sense of defectiveness or unworthiness, that shame does not necessarily make them behave better. Quite often it does the opposite. It can drive secrecy, defensiveness, blame shifting, numbing, aggression, addiction, and other ways of escaping from what they feel about themselves.
Some people have a much greater need for external validation because their internal sense of worth is unstable. Being desired, admired, chosen, pursued, or made to feel special can have an enormous regulatory function for them. It is not simply pleasurable. It temporarily changes how they feel about themselves.
That creates a very different vulnerability than someone who enjoys validation but does not need it in order to feel okay.
And once behavior starts conflicting with the person's self-image, shame can make honest self-examination even harder. The person does not necessarily think, "I am doing something terribly wrong, so I need to stop." They may instead start constructing explanations that allow them to keep doing it without fully confronting what it says about their choices.
The marriage was already bad.
My spouse does not understand me.
I deserve this.
Nothing has really happened yet.
This person is just a friend.
I have given up so much for everyone else.
I am finally doing something for myself.
At that point, the rationalization is serving a psychological purpose. It protects the person from having to look directly at the contradiction between who they believe themselves to be and what they are actually doing.
And I think this is where Brown's ideas about vulnerability, empathy, and wholeheartedness become especially relevant.
Shame thrives in secrecy and in the belief that if people really saw us, they would reject us. Vulnerability works in the opposite direction. It requires being willing to look honestly at what we are feeling, wanting, fearing, or doing, even when what we find is uncomfortable or unflattering.
Empathy also works against shame because it creates a way to face imperfection without either collapsing into self-condemnation or escaping into denial. If I can acknowledge that I am flawed, that I have needs, wounds, insecurities, and impulses I may not be proud of, without deciding that those things make me fundamentally unworthy, then I have much less need to hide from myself.
And that is part of what I understand Brown to mean by wholeheartedness. It is not believing that you are flawless. It is being grounded enough in your own worth that you can tolerate seeing yourself accurately. You can be vulnerable. You can admit uncomfortable truths. You can allow yourself to be known. You can experience empathy for yourself and for other people without using either as an excuse.
That matters enormously here because someone who can tolerate looking honestly at an uncomfortable internal state has an opportunity to interrupt it.
"I really like how this person makes me feel."
"I am seeking her attention."
"I am hiding this interaction from my spouse."
"I am angry and I like having someone validate my version of my marriage."
"I am starting to rationalize something I know crosses a boundary."
Those thoughts can be confronted before they become an elaborate secret life.
Someone who is deeply shame-bound may have much more difficulty doing that because honest examination itself is threatening. If acknowledging an inappropriate desire feels like proof that "I am a terrible person," then avoiding, compartmentalizing, minimizing, and rationalizing become psychologically attractive.
Two people can receive exactly the same attention, experience exactly the same attraction, and have exactly the same opportunity. For one person, it may activate a profound need for validation and a whole series of well-practiced defenses and rationalizations. For the other, it may simply register as attraction, followed by, "No, I am married," and the person moves on.
Those are not the same psychological starting points.
So I would not necessarily describe the difference as stronger character versus weaker character. I think there are deeper differences in how people regulate self-worth, tolerate uncomfortable feelings, process shame, practice vulnerability, examine their own motives, experience empathy, and respond when their desires conflict with their values.
That does not mean their actions are excused. They still have agency over what they do. Understanding why someone is more vulnerable to a behavior is not the same thing as removing responsibility for choosing it.
But it does help explain why it is harder for some people to resist than others. It helps explain why one person experiences temptation and walks away while another begins constructing the psychological machinery necessary to move toward it.
Their relationship to shame, their attachment wounds, their need for validation, their life stressors, their ability to tolerate vulnerability, and a host of other factors all come into play.
That is why I don't think "everyone is susceptible" tells us very much.
Everyone is human. Everyone has vulnerabilities. But we do not all have the same vulnerabilities, we do not regulate ourselves in the same ways, and we do not all have the same relationship with shame.
And shame is one of the more powerful forces pushing people toward maladaptive ways of dealing with themselves and with other people. Wholeheartedness, vulnerability, and empathy push in the opposite direction. They make it possible to see something uncomfortable in yourself without needing to hide it, distort it, or build a secret life around it.