I don't think it was over with Rearden until she met Galt.
I think Rand was always looking for her intellectual equal and thought she found that in ( ugh... what's his name?! Barbara's husband. Lol Gah! No memory... oh! Branden!!) But he turned out to not be in the end. Here's the point, Rand did love her husband, very much so. She got his permission to have an affair Branden. (From Barbara too.) There was no deceit. They are the only ones who need to understand that arrangement... it's not anybody's business.