Literally, aren't people who got cheated on always have half the fault?

Don’t get me wrong, I always give my sympathy whenever my friends tell me a story that their partner cheat on them, however, as I ponder the situation in neutral ground and as much as I would like to blame the perpetrator a part of me think that they partially brought this upon themselves, in a sense, they’re half at fault, they just didn’t realize it. Here’s my thought: They got in to the relationship by their own choice fully aware of the possible consequences in the future, it’s not like a gun pointed at their heads when they made the decision. It’s not fair to fully declare yourself the victim when you know you could possibly ended up become the victim and still go for it. If you trust someone and that person ended doing bad things then both of you are, literally, at fault. You, for deciding to trust them, and the cheaters, for lying to you. You won’t get cheated on if you didn’t trust the person in the first place. A simple cause and effect situation.

Some of them completely blame themselves for not being a good partner, others completely blame the cheaters. Me think both parties are half at fault, literally, of course. I don’t think it’s wrong to fully trust someone, it’s just that one thing should be made clear and acceptable by all participants in the drama. That thing is, you should be fair and accept that you initiated this issue and know that you share half the fault as the instigator. What do you think, folks? Do you agree with what I just said?