You did not fail by not making her leave. I am sure there will be other chances right around the corner.
Perhaps maybe you could do something simple like put the title to the van in her name. Or mention you are going to so that will not be a issue in her mind. So she sees you are not holding her back you are opening the door for her.
Just a thought.
I think you are doing great upheaving ones life reguardless how much it needs to be done is a hard choice to make.
