While you do not connect the dots, you have them all in your description. People were willing to believe her, because they wanted to be the fourth angle. By being in a triangle she was sending the message that a fourth angle is possible. By creating this story about you she was actually reinforcing that signal, making this possibility a discussion subject. Men are notoriously keen to have sex, especially on the age implied, and her behaviour was very promising. On the other hand, keep in mind that there is no randomness in thoughts or feelings you express. What you felt random could instead be serendipitous and she might even be right, but not in presenting that as something intentional.