For starters, in economics, the law of diminishing returns states that in any productive process adding one extra production factor, at a certain point, will start lowering your returns. In fact, if you keep adding too much, it can even hurt your returns! Think about studying: up to a point, the more and more extra hours you study, the less productive you are going to be, and you might hurt the outcome of your exam.
So, let’s try to apply this concept to love/relationships. Love makes us happy, so let’s assume we are trying to produce love. Our factors of productions are going to be time, empathy, feelings, care, money etc etc etc and of course - partners. Hypothetically, if you add all these production factors together, you can “produce” some love. Now, let’s hold all the factors of our “love production” constant and increase only the number of partners by one extra one (across time). According to the law of diminishing returns, our production of love is going to increase up to a certain point, then flatter, and then decrease!! Note, that our “love production” remains the same when you change a partner (all factors held constant). So, my question is: are there diminishing returns to partners, the more you have the more your love for the next one is going to diminish? Or, shall we just stick to the romantic view? I am an incurable one after all.