In my case, I would have pretty much the same list as Rick, plus:

7 - Because we have learned it as a defense mechanism when we feel hurt or rejected
8 - Because we don't have effective problem-solving and compromising skills
9 - Because we have low self-esteem and fear showing vulnerability

Me & H: 44
D7, D6, S3
Together: 20y, M: 17y
EA: 11/13/10, Sep: 12/23/10
EA becomes PA: Spring 2011
H filed for D: 09/06/12
D Negotiating began 2/15
OW seemingly gone on 3/15
Still negotiating D