How had Aunt Bex been a mother to Wren?

Aunt Bex had sewed Wren a colonial dress for the American Revolution unit they did in second grade. She never missed a T-ball game. She hung Wren's watercolors on her wall, even though as an artist, she probably knew they were terrible. Wren felt that Bex was her mother because she was the face she always looked for in a crowd.