You always know before your friend if the gf is cheating on him, just by observing. But one's own relationship is obscured by some sort of distorting effect. I

You always know before your friend if the gf is cheating on him, just by observing. But one's own relationship is obscured by some sort of distorting effect. I don't think it's a matter of 'IQ Drop'. I think it's more an example of 'Sunk Cost Fallacy' in that we don't want to admit to ourselves that we've wasted years or decades and also many thousands of dollars on a relationship that is very likely over, but maybe, just maybe, might be able to be turned around so that it wasn't all wasted.