Victor stops to rest in Paris and recover his strength.
He gets a letter from Elizabeth, asking him if he is in love with someone else.
Nope. Not unless by "love" you mean "obsession" and by "someone else" you mean "the monster."
He's still boneheadedly oblivious to the fact that the monster is planning to kill Elizabeth, so he decides to get on with the marriage and fight the monster, win or lose, to be free of him one way or the other.
Back in Geneva, he tells Elizabeth that he has a terrible secret—but he can't tell her until after they are married. Elizabeth is unfazed, so they get married and head off to a family cottage in the middle of nowhere.
(Just a hint, Shmoopers: never marry someone who has a big secret they can't reveal until after the wedding.)