It's very common for people to purchase engagement rings on loan. I had a friend who sold jewelry back in the 00s and he said it was pretty rare for someone to pay cash for engagement rings. Most people got 12-36 months loans.

It's possible this changed between 09-13 because of the recession, but I'd bet it's very common now that the economy is doing really well.

This might not be a mortgage, in the sense of being a lifetime payment. But it's a (semi-)secured loan.