There are many illustrious stories of betrayal both old and new: There's Christianity's Judas the Iscariot, Japan's WWII's Tokyo Rose, Rome's Marcus Brutus, American's Benedict Arnold, and Mexico's Dona Marina. In these diverse stories a singular point stands out: a clear-cut case of betrayal. In these examples the topic of betrayal is fleshed out, but we must not to be blinded by a definitive and unified moral lesson that stitches these diverse stories together. In fact, when betrayal befalls us, in our everyday, immediate experience, too often actually existing betrayal is far more messy and complex then these moralistic stories let on. It is this unbridgeable "gap" between our messy, inchoate experiences of betrayal one the one hand, and these "clean-cut" stories on the other, that opens up the darker, often unperceivable wound found therein.
Betrayal seems easy enough to understand, but there's a crucial twist. Let's first define the term betrayal, which happens when someone uses the trust you disclosed to him or her as a means of harming you. It's not a straight-shooting logic here as with revenge when a harmful act is returned in kind. Revenge is a 1=1 correspondence like Newton's so-called, "Third Law" whereas betrayal is like a karate fight in which one uses their enemy's weaknesses against them, throwing them off-balance and so on. Yes, that's right, the logic of betrayal actually uses you against yourself; it turns you into your own worst nightmare. But it's not exactly like you purposefully want to undermine yourself, you just happen to trust the wrong person--a someone who uses your vulnerabilities to inflict harm and damage on you.
Think of it like this: betrayal is like a trap into which you are lured, the only difference is you don't register it as a trap but more like a welcome party into which you helplessly fall prey. Some personalities haven't developed betrayal "filters" and so can't see betrayal coming, whereas other, more suspiciously bent personalities can never trust anyone enough to be betrayed in the first place. Often when someone trusts too quickly by failing to discern their partner's character and thus to protect themselves, they may well be asking for it.
This is why, I claim, if you've been seriously betrayed more than a few times, you may want to pause and do some serious self-reflecton. I'm not saying that you're at fault if you've been betrayed (everyone has), but if betrayal is a repeated pattern of devastating proportions it's possible that you may be suffering from what I call the "Victim Symptom" (VS) meaning that you perceive yourself as innocent, pure and trusting and your partner as corrupt, counterfeit, and deceptive. It's a "me vs. them" mentality, hence the VS symptom.
The basic problem with this is that a victim-prone person may project an either/or logic onto their partner, but, and this is the tragic up-shot, there's a self-fulfilling prophecy that rears it's ugly head in the form of betrayal. "I trusted him so much, and he violated me" and so on. But there's more: Sometimes the victims actually get great enjoyment out of their own downfall through disclosing trust in unwarranted, even deceptive ways. And this very enjoyment or pleasure is reason enough to desire it again and again. The upshot is simple enough (and this is the perverted part found inside the dark kernel of betrayal): the one suffering from repeated betrayals may not actually trust their partners at all and may even be unable to trust full-stop. What this boils down to is that people suffering from VS are incapable of the action we call "trust".
They may even mask the weakness of untrusting by overly trusting in all the wrong ways and for all the wrong, often-selfish reasons. That's the thing about a "symptom" it's something that you suffer from, but you're not willing to take actions to relieve yourself from this suffering and the reason why is because you actually enjoy your symptom. You can even get off on the symptom. Take the example of the gambler who repeatedly looses money in bets, but they want more not because they think they'll eventually hit the unlikely jackpot, but rather because they get off on actually loosing bets; the bigger the loss the more they enjoy it.
The one who suffers from repeated bouts of relational betrayal should seriously consider their part in co-creating the tragedy that continues to befall them. Betrayal in other words, often betrays the one betrayed, and that's the perverse angle one must learn to perceive.