Or HaChaim on Numbers 30:16/אור החיים על במדבר ל׳:ט״ז

1 ואם הפר יפר, "and if he surely decides to disallow, etc." This verse means that even when the vows he now decides to disallow are the type which he could have disallowed during the prescribed period, now that he has waited too long, he can no longer exercise his authority but must bear her guilt (if she violates her vow).