First time hope buyer, help?!

Okay, so this is kind of complicated and everything i search online sends me in circle so I am hoping to get some help here.

My fiancé and I have decided it is time to make the step to purchase our first home. When we first spoke with the lady at the bank she said everything looked great we could get a usda loan, and gave us a price point, and even put us in touch with a realtor agent. After months of looking at house after house we finally found "the one", and it was even below our budget. So we go in to the bank to make an offer on the home and the same lady tells us that something came up and my fiancés credit history is not long enough fro us to receive the loan despite his 765 credit score. This was never mentioned before. Now we have gotten our hopes up and are looking into our other option. I know there is a fha loan, but I really need the details on it because as I mentioned before everything I find online send me in circles. We are both first time home buyers so any information is greatly appreciated. Thanks in advance!

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