Unfortunately, there are different standards/unwritten rules for different countries. One in-person visit is typically enough for a country in Western Europe. But if you're fiance is from Africa, a predominantly Muslim country, China, Russia, etc. the rules aren't the same. My fiance is currently in administrative processing. She has several university degrees and no criminal record, but being from Belarus created added scrutiny in the process. Immigration officers rarely look at the character and merits of the individual, but the country they come from as a whole. The visa applicant could walk on water, but none of that matters if they're from a heavily scrutinized country. If my fiance would've been from Western Europe, she would've been in the US months ago. I've lived in sanctuary cities where people in the country illegally could do practically everything a legal citizen could do except vote. Yet, those who follow the rules and opt to go through the legal immigration system, are put through seemingly endless wait times and other problems. It's not fair, but it's something we can't change, at least not in the short-term. Assuming there's not something about the denial you're not disclosing, you may need to move to her country, get married and live for a season while you apply for a marriage visa.