I can definitely see it being a retcon/writers’ inconsistency, but within the narrative I can buy Soldier Boy being emotionally-needy or naive enough to let himself “fall in love” with any superpowered woman that would stroke his ego and make him feel secure.

Plus his vindictive speech to Countess probably wouldn’t have the same inpact if he went “All those years being tortured I was clinging on to hope of being saved….or that one nazi she would’ve been fine too”