You cannot convert all emotional energy into useful work (happiness). Some is always lost to friction.
The romantic solution, according to page 47: "For a cyclic process, the net heat absorbed equals the net work done." In other words, a healthy relationship cycles. You give, they give back. Energy flows in a loop. The Physics: The entropy of an isolated system never decreases. $\Delta S \geq 0$. Heat flows from hot to cold, not the other way around. Solucionario Zemansky Calor Y Termodinamica Sexta Edicion
It is important to clarify something upfront: (the solution manual for Física Universitaria or Calor y Termodinámica by Zemansky & Dittman) is a technical resource for solving physics problems involving entropy, heat engines, and adiabatic processes. You cannot convert all emotional energy into useful
The solucionario doesn't forbid it. It just demands an external energy source. That source is courage. The Physics: Efficiency = $1 - \fracT_coldT_hot$. No engine is 100% efficient. You give, they give back
You and your love interest enter a room (the system). At first, you are different temperatures—you are shy (cold), they are boisterous (hot). But there is a third element: the terrible office coffee machine (body C).
All you can do is calculate your own internal energy, respect the laws of thermodynamics, and hope that when you open your system to another person, the heat flows both ways.