1.
If someone goes off with another person, they leave their husband, wife, or lover and have a relationship with that person.
I suppose Carolyn went off with some man she’d fallen in love with.
PHRASAL VERB: V P P n
2.
If someone goes off with something that belongs to another person, they leave and take it with them.
He’s gone off with my passport.
PHRASAL VERB: V P P n