I do a risk-benefit analysis
Lol don't even know how to begin applying one of those to this situation.
Hold them at arms' length before you can ascertain whether your instincts have any truth to them? That way you don'thave to break contact altogether nor do you trust them completely/
Yeah, probably best to do this in the future.
But like what if it's too late?
Say you have a friend, and you think that friend is taking advantage of your good nature, your gut instinct is saying one thing, but you rationalise it as "no berbs, you are just being paranoid", but still mostly, daily, you feel the other part of you laughing at what a mug you are.
Is it better to just cut people off as soon as you feel that start to build?
Asking is pointless, nothing anyone says is ever believable, only provable.