I stand corrected

And here's why I'm so not an economist- even though the author deleted his comment, here's what it said:

Not all of your comments on sunk cost are accurate. For example, if you're dating someone and you play kickball with him, the cost of having to see your ex at kickball events is not "sunk". That is, you won't have to bear that cost if you break up with him. It may very well be the case that the cost of having to be with someone you don't like exceeds the benefit of not having awkward moments during kickball--but the awkward moments are not a sunk cost, strictly speaking. It is rational to take them into account.

So I was wrong, apparently, which is why I'm not an economist.