(Pro 5:16 KJV) Let thy fountains be dispersed abroad, and rivers of waters in the streets.
The word picture being drawn here is of a cistern and the use of stored water. The advice is to not throw away a valuable resources. The literal application behind the figurative speech is to keep your affection and sexual contact within the bonds of marriage and not throw them out into the general public. That seems pretty simple.
A cistern would obviously be limited in the water it will hold but I never stopped to think that even a well will run out of water if too many people are using it. Stewardship applies to our sexual facet as well as our financial. God blesses us and we are expected to use them in righteousness.
So? Don’t waste your affection on those outside of your personal covenant. Remember that water running down the street is dirty and gets dirtier as it runs.