What you said rings so true for me too. My ex just did not think his family loved him enough. It was quite pathetic and really when you think of it so immature. He thought OW and son could provide him with what is missing within.
Me: 46 H:44 Together: 25 years Married: 20 years Separated: 11-30-06 Divorced 12-21-07 OW: EA began 2005 PA began end of 2006 3 children,20, 16, 6 ex asked for forgiveness 01/16/11
