Here is a thought. Jennifer does NOT have strong parenting skills, which is something that abounds in Salem. Her children spent most of their lives in boarding schools while both she and Jack concentrated on their careers!
I also never thought of Jennifer as decisive. WE all remember the problem she had in deciding between Jack and Daniel. Thinking back we can also remember her romance with Frankie, both the first and ssecond time. She could never make up her mind. Kind of explains the actions of Abigail with Chad and Cameron. Like mother like daughter!!
Add to all of that, she is extremely guilty for JJ being away when Jack died, never telling JJ about Jack (although I don’t think it is JJ business as it all happened long before JJ was born). She keeps saying she needs to be there for her son, but she just cannot make a decision and stick to it.
In my opinion she has always been weak in her personal relationships. I guess she just cannot understand how Daniel might pick scummy Teresa over sophisticated Jen. It is all about Jen–"you know I hate her, how could you be with HER". Bottom line it is NONE of her business!!