First Girl After All is a narrative technique of concealing a character's first Love Interest for as long as possible until the moment when it's most dramatically shocking to the audience, usually at or near the climax of the plot. This is accomplished either by never making it clear who the First Girl is, or by misleading the audience into believing that another character is the First Girl.

After much of the story, we approach The Reveal, the Final Battle, the Grand Finale, or some other tense moment, and it seems like the "Second Girl" in the Love Triangle (or Last Girl in the Love Dodecahedron) is going to win. But something suddenly "clicks", and the story reveals that they first met when they were children! But wait! This could only have possibly happened BEFORE he met the First Girl. This can only mean that the girl everyone thought was the Second Girl is the First Girl After All.