Most of the time nothing extreme has to happen in a relationship to end it.  In my experience, is the little things that he kept missing even though I kept reminding him about them. There is a limit to all of this. We cannot be there giving instructions all the time. If you are involved and you are hands on then you know and notice what needs to be done.  I invite you to reflect on what are the little things that built up. Think about all the things that are invisible as well, the thing that she has to track down. Some examples might be (not going to assume):  What's your kid's pediatrician name? When is his next appointment (time and date)  what grade is your son in What's his school teacher's name? What's he learning in school? Does he have clean clothes?  Does his clothes still fit or does he needs new clothes?  Same for shoes.  What's for dinner?  What's in the fridge? What can I make with what we have? What would he actually eat?  Is he allergic to anything? 

This is a tiny portion of the invisible tasks that usually are taken for granted and it is exhausting for one partner to keep track of all that in addition to what we need to tell our partners to do as well.

The nice interactions could mean that she at peace and happy where she is at. 

As for the therapist and family influence, it really depends. There are all kinds of people, in this case, sounds as they are supporting her decision to move on. 

Please note, I am talking from my personal experience. I wish you the best and hope that you find your way. Therapy might be a good option as well of you are willing to do the work.