The Bean Trees Lou Ann Ruiz Quotes

"What's so funny?" Lou Ann wanted to know. "I hope I can even fit into this dress. I should have tried it on first. I haven't worn it since before Dwayne Ray." I had noticed that Lou Ann measured many things in life, besides her figure, in terms of Before and After Dwayne Ray. (7.76)

Why does Taylor make note of the fact that Lou Ann measures her life in terms of "Before and After Dwayne Ray"? Is Lou Ann simply using a memorable event to help her keep track of time, or is Taylor suggesting that there's something self-damaging about the way Lou Ann defines herself in relation to her child?