Physiological potency, the desire to attract someone romantically, and, on the other hand, the need to stop that attraction in a certain situation or use it for something else, are all examples of such problems.
In short, that is the essence of what needs to be done on the physical level to make this happen. It is the love potion, the philtre, the mystic mixture that, once drunk, will fill you with love, passion, desire, and lust. It will also awaken the ancient fons vitae, which the ancient Hellenes saw as the source of all cosmic creation and all living generation.
So, the potion is at least a theoretically effective tool for securing and keeping the desired object's romantic interests. It also works as an apotropaic tool to take love that the agent thinks is going in the wrong direction and put it in the right place.