Nothing much is said about Margaret, as she has no screen time or identity shown.
It is said Hoffman had plans to Marry Margaret, but had interest in Anderson as well. When Anderson asks about their marriage, Hoffman replies with "I just don't know anymore, I guess". Hoffman also gets a little defensive when questioned, asking Anderson "what more do you want from me", and expresses worry with Margaret possibly wanting to have kids with him.
It is implied Margaret dies sometime before or during the strike, as Hoffman tells Adam that Margaret is missing, and that there hasn't been any sign of her even after having the checkpoints searching for her.