Who is Joe Tully from Drowning Ruth and what is their importance?

Joe Tully is Amanda Starkey's first boyfriend, Joe falls short of her parents' expectations and she is packed off to a female relative to get over him. Later, while living with her widowed brother-in-law Carl Neumann, Amanda again grows close to Joe, who helps Carl build the cabin on the island. Joe and Amanda go to movies and fish fries on Friday nights but she resists anything more.