Knowing Kaley´s past dating history this relationship doesn´t look to last but perhaps it´s different this time and she has learn something.
My humble guess is that she wanted a baby and Karl didn´t, so they divorced.
A post from Kaleys Instagram on the 6 of May, and it looks like the same dress to me.
She was attending The John Ritter Foundation from the heart LA Gala
I have noticed that Karl hasn´t posted anything on Instagram since the 15th of May, about the same time Kaley started posted about Tom. This could of course just be a coincidence but it´s fun to speculate.