You must have missed the testimony. Mr. Rentz had been fearful for quite some time that Nancy was involved in a volatile situation and suggested she leave. Brad had taken Katie's passport, making it impossible for her to flee to Canada with both girls.
Mr. Rentz had a career in social services and was acutely aware that domestic situations such as Nancy's could turn violent at any time. Nancy felt that Brad would never hurt her.
Something either frightened her or changed her mind as evidenced by the call to the realtor to start looking for an apartment ASAP.
It's too bad she didn't get "out" sooner. Now she is statistic like the thousands of women killed because of not responding to the warning signs earlier.
That relationship was a powder keg. Neither individual was behaving well. Add alcohol to the mix and the unthinkable happened.
Google "divorce murder" and see the number of results that are found: About 19,100,000 results (0.16 seconds)
I quoted your post on purpose, even though it is long. This is the exact reason why all those in defense of Brad, focus on the computer evidence....they don't want the jurors to remember and focus on the emotional part of this case and so many otheres. Woman, that can't imagine the danger they are in and die trying to leave a horrible marriage. It is real, and happens every day. This is really a simple, common, straight forth, and tragic case of a bad marriage and a man that didn't want to pay. Simple and common, but the defense will try every time to make it confusing and complex.....as in this case, hence, the computer evidence.