Given that G'raha declares the WoL rejoining with Ardbert was impossible—while not so much as mentioning Minfilia or Ryne—I'm inclined to believe that they did not rejoin. Rather, that it's as Emet-Selch said: Ryne "consumed" Minfilia. Their relationship may be more akin to Hraesvelgr and Shiva, or Diabolos and Scathach, than the WoL and Ardbert's or Lohgrif and Gaia's.