Radical difference in eyes of most woman.
Husband is a man with biggest man’s problem solved. It is responsibility. Men are completely different from women in this aspect.
Boyfriend can flee or disappear at any moment. He is not technically and legally responsible for his wife and her welfare. And he did not took this commitment.
Taking such commitment in eyes of 4 people in a dark room is not counted. It should be done with witnesses.
That’s how real social psychology works.