"Who is not betrothed" — the Torah specifies that the seduction law applies to a virgin who has not been betrothed. The Mekhilta records a disagreement about the scope of this exclusion.
Rabbi Yossi Haglili read the verse strictly: "not betrothed" excludes any woman who was ever betrothed — including one who was widowed or divorced during betrothal. Once a woman has entered betrothal, even if it ended, she is no longer within the scope of this law.
Rabbi Akiva disagreed. He argued that even a woman who was widowed or divorced during betrothal remains within the law. His reasoning was practical: a father can annul his minor daughter's vows, and he can accept her penalty payment (knass). These two powers apply whether or not she was previously betrothed. If the first power (annulling vows) survives widowhood or divorce, the second power (collecting knass) should survive as well.
The dispute turns on how much legal weight to give to a dissolved betrothal. Rabbi Yossi treated betrothal as a permanent status marker — once it attaches, it never fully disappears. Rabbi Akiva treated it as a dissolved arrangement that leaves no residual effect on the father's rights. Both views have internal coherence, and the Mekhilta preserves both as legitimate readings of the same Torah phrase.