Don Richardson is a soldier, veteran of the War in Afghanistan. He is also Amelia's husband.
Don was thought to have been killed in an overseas military mission. However, after a few months, Don himself reveals he is alive by calling Amelia. Some time after, he made his way back to Amelia's locale.
Upon returning, he and Sam discussed things. While not being completely happy with the situation, he accepted it by saying Amelia knew what was best for her and that it was her decision. Don also urged Sam to follow suit and give respect to Amelia's choice, if the ex-hunter really loves her. He was last seen with Amelia watching TV in her living room by Sam. This implies they are back together.