One of the fascinating aspects of this novel is the way in which it presents us with a whole gamut of different reactions to death. Whilst Jack becomes obsessed with finding his daughter's murderer, Abigail, his wife, seems to just want to do what she can to move on with her life. Part of this, as narrated to us by Susie, is the affair that she has with Len, as she feels increasingly distanced from her husband because of their different reactions to their daughter's disappearance and death.
It is in Chapter Twelve where the affair occurs, and, according to Susie, when Abigail asks Len to kiss her it is a "beg for leniency:
My mother was moving physically through time to flee from me. I could not hold her back... I knew what was happening. Her rage, her loss, her despair. The whole life lost tymbling out in an arc on that roof, clogging up her being. She needed Len to drive the dead daughter out.
Thus the affair that Abigail has with Len is about her need to move on, to "drive the dead daughter out" and to find "new life" on the other side of her kiss with him. She cannot dwell permanently on what has been lost and her desire to move on is expressed in her affair.