TV executives in the 60s had yet to discover you could arc a storyline over several seasons. Every episode of a show was a stand alone drama. It needed a touch of romance, but the romance had to be done and dusted within forty minutes. James Kirk wasn't so much a Lothario, as the victim of a TV trope. He loved all those women truly and sincerely and was devastated when circumstances beyond his control forced him to leave them behind. Then between episodes someone pushed the reset button and he forgot all about them. He wasn't unique in this. Every TV hero had a similarly bumpy love life. What happened in an episode stayed within an episode. Our heroes had their hearts broken, underwent trauma, did things that would scar any normal human being for life, then popped up again next week as innocent as ever. TV cowboys got caught up in more gunfights and killed more people than Wyatt Earp, Wild Bill Hickcock and Billy the Kid combined yet never lost their deep-rooted aversion to violence.