When this topic was raised I tried googling it, and all I found was transactional vs. relation attitudes of businesses to their customers, as a marketing strategy. Basically the major difference seemed to be that a transaction is over once both parties delivered, they try to make that quick to happen, an ideal vendor delivers fast, an ideal customer pays fast, and from that point on they owe each other nothing, not even another transaction. They can do 1000 transactions and still have no loyalty to each other, still willing to do the next transaction with someone else. A relational attitude is more ongoing, has a sense of loyalty, and debts are not necessarily quickly cleared, and even when they are cleared they still feel they mutually owe loyalty. Again, I am talking about how these terms are applied in marketing. E.g. http://www.wizardofads.com.au/transactional-vs-relational-shoppers/

It seems to me that the central idea of the transaction is for both parties to deliver quickly and close the transaction, to get what they want quickly and explicitly not owe anything to each other in order to keep their complete freedom. While a relation can be a long series of I-owe-you, you-owe-me with mutual loyalty, you get what you want, but in many cases you are owed a bit more or you owe a bit more, so more of a dynamic balance.

It seems to me that the essence is that transactional atttitudes aim at freedom, non-attachment, they aim at closing the transaction clearly and clearing all debts, so that both are free to choose without any obligations to each other. This necessarily implies a short-termist attitude. So the rule seems to be "minimize the time transactions stay open", for transactional attitudes. Relations are more okay with open transactions, and probably will not compartmentalize much the mutual services delivered into individual transactions.

I don't fully understand how it works in relationships and sex. Clearly, in prostitution the customer pays either shortly before or shortly after sex was done, in order to minimize the time the transaction stays open. A couple could for example work so that the man wants sex more than the woman, and the woman wants attention and talking more than sex, so they exchange this, and my hunch is that a transactional couple would pay quickly so that they can always break up without obligations, while a relational couple wound not mind ongoing debts, and would not probably account for debts as such, they would probably not say "we are having more sex than I want so now you must talk to me more than you want" but more likey they would understand the situation as both, in an ongoing way, trying to provide what the other wants, and no accounting or clearing of debts happen.

For a transaction to be a transaction, the things exchanged need to be split up into commensurable packages, €2 for a beer or a favor for a favor or fifty minutes of attention for a blowjob or something like that. So they know how much payment closes the transaction. I think in relations the whole splitting up does not happen.

For example, if you own a business and hire a manager to run a subsidiary, the general idea is that you are paying enough for him to make a comfortable living and he is working as much as necessary to make the subsidiary run okay, overtime is not specifically accounted or paid for for managers, and there is no specific job description, just do everything to succeed. So the idea is to have the kind of relation where you both provide what the other needs in a general, broad way. While things like paying factory workers per piece or miners per ton or sharecroppers as a share of harvest is more transactional.