That rule constitutes good policy. We don't want to force Ray to wait until next week to sue, given that you have evidently made clear your intention to breach. Better that he should wrap up his dealings with you and get to work finding a substitute transaction.
The rules pertaining to damages for repudiation contain a loophole, however, that does not so clearly constitute good social policy. That subsection alluded to above—the subsection in R. (2d) of Contracts § 243(3)—provides:
Where at the time of the breach the only remaining duties of performance are those of the party in breach and are for the payment of money in installments not related to one another, his breach by non-performance as to less than the whole, whether or not accompanied or followed by a repudiation, does not give rise to a claim for damages for total breach.
How does the § 243(3) work? Suppose that you contract with Sally to take possession of her car now and pay for it over the next year, making monthly payments with interest. Six months into the deal, you say to Sally, "The deal is off. Contrary to my promise, I am not going to pay you anything more for the car." You have just repudiated the contract. Section 243(3) says, however, that Sally does not yet have a claim for damages equaling the remaining six months' of payments. Rather, she can sue you only for each month's payment as it comes due.
Note that we would have a different result if the contract were not one-sided. Suppose, for instance, that you contract with Mike to have him clean your pool once a month for the next year. You then repudiate your agreement after six months. Mike, in contrast to Sally, can bring suit now for all the remaining payments you have repudiated. See § 243(2).
Why that difference? I've poked around a bit and found no real explanation. Comment c to § 243 simply proclaims,
Not too helpful, that. Nor did a search of the law reviews or ALR turn up anything more on-point. I found cases applying the rule "restated" in § 243(3), usually framing it as an example of a more general limitation on the availability of damages for repudiation of a bilateral contract, but without any explanation or policy justification.
It is well established that if those duties of the party in breach at the time of the breach are simply to pay money in installments, not related to one another in some way, as by the requirement of the occurrence of a condition with respect to more than one of them, then a breach as to any number less than the whole of such installments gives rise to a claim merely for damages for partial breach.
The question about the reasons for the rule in R. (2d) of Contracts § 243(3) arose from one of my Contracts students, after our last class. He, I, and another student worked out a fair explanation: A party who has already suffered one repudiation should not have to continue performing for the breaching party. Sally, because she has already completed all the performances she owes you, does not face that problem. But Mike, who still owes you monthly performances, should not have to keep cleaning your pool in vain.
What do you think, dear readers? Does that justification of § 243(3) make sense to you? Or have you got a better explanation?