A Heter Meah Rabbanim is not a divorce. It does not dissolve the marriage. It is part of the Cheirem of Rabbeinu Gershom against marrying a second wife. You need a HMR to marry a second wife.
And Oomis: A woman does not have to accept the Get. It can be given Ba’al Korchah. She has several ways to avoid him being able to give it to her, but if he gives it to her they’re divorced.