My honest opinion is, he is separated 6 months. He shouldnt even think about dating, and Im not sure if its even legal to date while you're separated. Even then I'll tell you why its not a good idea. When separation or divorce happens to a person, they grieve similarly to when a person dies. It's a great change and that causes much stress. To add on the stress of dating someone new is really not good for him, especially when its compounded by the fact he has young children.
So my recommendation is either find someone else, or be prepared to wait it out for a while, if this is what you want. Hes going to need plenty of time to heal from this drastic life change.
The only true wisdom is in knowing you know nothing.